1st August, Monday

A-1

Plenary Talk 1 Bernard Dieny

13:30-14:15, Monday, August 1st Room: 1st Lecture Hall Chair: Yuan-Chieh Tseng / National Chiao Tung University

Top-down engineered magnetic micro/nanoparticles for

biotechnology and biomedical applications

Joisten H. 1,2 ; Leulmi S. 1; Iss C. 1; Morcrette M. 1; Naud C. 1; Dietsch T. 1; Ortiz G. 1; Hou Y. 3; Livache T. 3; Calemczuk R. 3; Carriere M. 3; Sabon P. 1; I.Joumard 1; Auffret S. 1; Dieny B. 1

1 SPINTEC, Univ.Grenoble Alpes / CEA / CNRS, F-38000 Grenoble, France.

2 CEA, LETI, MINATEC Campus, F-38000 Grenoble, France. 3 SYMMES, Univ.Grenoble Alpes / CEA / CNRS, F-38000 Grenoble, France.

In the field of biotechnology, magnetic nanoparticles are increasingly used for a variety of applications since they allow to exert forces and torques on biological species. Based on top-down approaches (deposition, etching, lift-off), several types of micro/nano particles were prepared for various purposes. They include synthetic antiferromagnetic particles, vortex microdisks [1], magnetite multidomain particles, magnetic nanoswimmers. A first part of the work has aimed at controlling the agglomeration/dispersion of these particles [2]. To avoid the agglomeration of the particles in solution, these particles are designed to exhibit superparamagnetic like response and must have a susceptibility below a certain critical threshold to avoid their mutual self-polarization. Thanks to their anisotropic properties, they offer new degrees of freedom in their manipulation when dispersed in solutions [3]. This allows designing ferrofluids with novel properties. In particular interesting optical properties can be obtained. Concerning biomedical applications, a recent approach for cancer cells destruction was proposed, based on the triggering of cancer cell spontaneous death through the mechanical vibration of anisotropic magnetic nanoparticles attached to the cells membrane at low frequencies (20Hz) and in weak magnetic fields ( a few mT) [4]. The induction of cancer cells apoptosis was demonstrated in earlier work on glioblastoma cancer cells [4] and in this study with NiFe vortex particles on renal human cancer cells [5]. Statistical analysis of apoptosis triggering was characterized by flow-cytometry and caspases activation studies. These results open great perspectives for new cancer treatments with reduced side effects. [1] Leulmi, S., Joisten, H., Dietsch, T., Iss, C., Morcrette, M., Auffret, S., Sabon, P., Dieny, B., Appl.Phys.Lett. 13, 132412 (2013) [2] Joisten, H., Courcier, T., Balint, P., Sabon, P., Faure-Vincent, J., Auffret, S., Dieny, B., Appl.Phys.Lett.97, 253112 (2010) [3] Courcier, T., Joisten, H., Sabon, P., Leulmi, S., Dietsch, T., Faure-Vincent, J., Auffret, S., Dieny, B., Appl.Phys.Lett. 99, 093107 (2011). [4] D.H. Kim, E.A. Rozhkova, I.V. Ulasov, S.D. Bader, T. Rajh, M.S. Lesniak, and V. Novosad, Nat. Mater. 9, 165–71 (2010). [5] Leulmi, S., Chauchet, X., Morcrette, M., Ortiz, G., Joisten, H., Sabon, P., Livache, T., Hou, Y., Carriere, M., Lequien, S., Dieny, B., NANOSCALE, 7, 15904 (2015).

A-2

Session AA Fundamental Properties & Computational Magnetism I

Monday Afternoon, Aug. 1st, 2016 Room: 3rd Lecture Hall Chair: Yuan-Ping Feng/ National University of Singapore

Konstantin A. Zvezdin/ A.M.Prokhorov General Physics Institute

14:15-14:45 (AUMS Young research award) AA-01 Nontrivial dynamic behavior of magnetic splitons: Strong inertial effects of magnetic skyrmions Ki-Suk Lee School of Materials Science Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Korea. 14:45-15:15 (Invited) AA-02 Microwave spintronics. From fundamentals to applications Konstantin A.Zvezdina,b,c

aA. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilova st. 38, Moscow 119991, Russia bMoscow Institute of Physics and Technology, Institutskiy per. 9, Dolgoprudny 141700, Russia cRussian Quantum Center, Skolkovo, Moscow Region 143025, Russia 15:15-15:45 (Invited) AA-03 Quantum Transport in 2D Group-IV monolayers and TIs and their Potential Applications Gengchiau Liang Department of Electrical and Computer Engineering, National University of Singapore, Singapore 15:45-16:15 (Invited) AA-04 2D Materials and Devices for Spintronics: First-principles Studies Qingyun Wu(a), Minggang Zheng(b), Sandhya Chintalapati(c), Lei Shen(d), Yuan Ping Feng(e,f)

(a) Department of Materials Science and Engineering, National University of Singapore, Singapore (b) Data Storage Institute, A*STAR, Singapore (c) Division of Physics and Applied Physics, Nanyang Technological University, Singapore (d) Engineering Science Programme, National University of Singapore, Singapore (e) Department of Physics, National University of Singapore, Singapore (f) Center for Advanced 2D Materials, National University of Singapore, Singapore

16:15-16:30 AA-05 First-Principles Analyses of Electronic Structure of Multiferroic Nd doped BiFeO3 Solid Solution Peng, Yi-Ting (a), Tu, Chi-Shun (b) Hsiao, Ching-Hung (a), Ouyang, Hao (a) (a) Materials Science and Engineering, National Tsing Hua University, Hsinchu City,Taiwan. (b) Physics, Fu Jen Catholic University, New Taipei City, Taiwan. 16:30-16:45 AA-06 Interfacial Dzyaloshinkii-Moriya Interaction Induced Domain Wall Depinning Anomaly H. K. Teoh, S. Goolaup, W. S. Lew School of Physical and Mathematical Sciences, Nanyang Technological, University, 21 Nanyang Link, Singapore 637371 16:45-17:00 AA-07 Shape-dependent Skyrmion dynamics under spin-orbit torque I. Purnama, G. W. Shiguang, W. L. Gan, and W. S. Lew School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 17:00-17:15 AA-08 Bi3+ Doping Induced Suppression of Spin Flop Transition in DyMnO3 D. Paul Joseph(a), N. Pavan Kumar(a), J.W. Lin(c) , W.C. Chen(b), J.G. Lin(b)*

(a) Department of Physics, National Institute of Technology, Warangal, Telangana State, 506004, India. (b) Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan. (c) National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan.

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Session AB Spintronics Materials and Devices I

Monday Afternoon, Aug. 1st, 2016 Room: 1st Lecture Hall Chair: Shang-Fan Lee/ Academia Sinica

Masaki Mizuguchi/ Tohoku University

14:15-14:45 (Invited) AB-01 Advanced Spintronic Materials Based on Ordered Alloys Koki Takanashi Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan 14:45-15:15 (Invited) AB-02 Spin Currents in Antiferromagnets Axel Hoffmann(a), Wei Zhang(a), Stephen M. Wu(a), Hilal Saglam(a,b), Joseph Sklenar(a,c), M. Benjamin Jungfleisch(a), Wanjun Jiang(a), Yaohua Liu(a), John E. Pearson(a), Suzanne G. E. te Velthuis(a), J. Samuel Jiang(a), Anand Bhattacharya(a), John B. Ketterson(c), Frank Freimuth(d), Yuriy Mokrousov(d), Amit KC(e), Pavel Borisov(e), David Lederman(e), (a)Mater. Science Division, Argonne National Laboratory, Argonne, IL 60439, USA (b)Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA (c)Dep. of Physics and Astronomy, Northwestern Univ., Evanston, IL 60208, USA (d)Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany (e)Dep. of Phys. and Astron., West Virginia Univ., Morgantown, WV 26506, USA 15:15-15:45 (Invited) AB-03 Soliton-like magnetic domain wall motion induced by the interfacial Dzyaloshinskii-Moriya interaction Teruo Ono Institute for Chemical Research, Kyoto University, Gokasho, Uji, Japan 15:45-16:15 (Invited) AB-04 Spin current coupled with dynamical magnetization Kazuya Ando Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan 16:15-16:30 AB-05 Magnetism modulation of Fe/ZnO hetero-structure explored by in-situ x-ray absorption spectroscopy and electrical

characterization Shu-Jui Chang(a), Shao-Hua Lo(a), Po-Chun Chang(b), Wen-Chin Lin(b), and Yuan- Chieh Tseng*(a) (a)Dept. Materials Science & Engineering, National Chiao Tung University, Hsinchu, Taiwan. (b)Dept. Physics, National Taiwan Normal University, Taipei, Taiwan. 16:30-16:45 AB-06 Magnetic Property of Fullerene C20 : A First-Principles Study Icuk Setiyawati and Yu-HuiTang* Department of Physics, National Central University, Jhong-Li, Taiwan 16:45-17:00 AB-07 Van der Waal epitaxy: a new perspective for flexible spintronic devices Ping-Chun, Wu(a)(f), Ping-Fan, Chen(b), Chun-Hao Ma(c), Ha Tai Duy(c), Kun-Hong Wu(d), Qing-He(e), Yi-Chun Chen(d), Chun-Fu Chang(f), Ying-Hao, Chu(a)(b)(c) (a) Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (b) Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (c)Department of Electrical Engineering, National Tsing Hua University, 30013 Hsinchu, Taiwan (d) Department of Physics, National Cheng Kung University, Tainan City 701, Taiwan (d)Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (e)Department of Physics, Durham University, Durham DH1 3LE, United Kingdom (f)Max Planck Institute for Chemical Physics of Solids, Noethnitzerstr. 40, 01187 Germany 17:00-17:15 AB-08 Spin Transport Calculation in Novel nm-scale Magnetic Junctions Yu-Hui Tang Department of Physics, National Central University, Jhong-Li, Taoyuan, Taiwan

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Session AC Magnetic Recording I/Magnetic nanostructures

Monday Afternoon, Aug. 1st, 2016 Room: 2nd Lecture Hall Chair: Jing Sheng Chen / National University of Singapore

Hiroaki Muraoka / Tohoku University 14:15-14:45 (Invited) AC-01 Microwave assisted switching and its application to 3D recording system N. Kikuchi(a), S. Okamoto(a), H. Suto(b), Y. Nakayama(c),(d), O. Kitakami(a), K. Kudo(b), T. Nagasawa(b), T. Kanao(b), K. Mizushima(b), R. Sato(b), T. Shimatsu(c), (d) (a)Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan (b)Corporate Research and Development Center, Toshiba Corp., Kawasaki, 212-8582, Japan (c)Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, 980-8578, Japan (d)Research Institute of Electrical Communication, Tohoku University, Sendai, 980-8577, Japan 14:45-15:15 (Invited) AC-02 Control of microstructure of FePt-X (001) filmsfor HAMR through interface modification and doping Jingsheng Chen Department of Materials Science and Engineering, National University of Singapore, Singapore 15:15-15:45 (Invited) AC-03 Media Design and Challenges for Heat-Assisted Magnetic Recording for 2Tbpsi and beyond Eric K.C. Chang, Pin-Wei Huang, HassibAmini, YingguoPeng, Li Gao, Yinfeng Ding,Timothy Klemmer,Xiaobin Zhu, Alexander Q. Wu, Yukiko Kubota, Jan-Ulrich Thiele,GanpingJu Seagate Fremont 15:45-16:00 AC-04 Decomposable Cu3N layer for reducing L10 FePd ordering temperature Ching Hung Hsiao, Chuenhou (Hao) Ouyang Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

16:00-16:15 AC-05 Curie temperature measurement of FePt film by infrared reflectivity Seong-Jae Jeon, Koichi Akahane, Shin Saito Department of Electronic Engineering, Tohoku University, Sendai, Miyagi, Japan 16:15-16:45 (Invited) AC-06 Reversible Hydrogenation Effect on Magnetism of Pd-related magnetic thin films and nanostructures Wen-Chin Lin,* and Yu-Chuan Chen Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan 16:45-17:00 AC-07 Study of the Interfacial interactions and the relevant Ferromagnetism of Ag/TiO2 core-shell nanoparticles Yin-Ting Hsiao, Eric Nestor Tseng, Pin-Yu Chen, William Lee, Shih-Yun Chen* Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 17:00-17:15 AC-08 Positive exchange bias in potassium split graphene nanoribbons M. Venkat Narayana(a), Srinivasa Rao Singamaneni(b), and Suryanarayana Jammalamadaka(a) (a)Magnetic materials and device physics laboratory, Department of Physics, IIT Hyderabad, Telangana-502285, India (b)Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709, USA

A-5

Poster Session BP (Migaku Award) Best Poster Award

Aug. 1st to Aug. 3rd, 2016 Room: Multifunction Room Chair: Wen-Chin Lin/National Taiwan Normal University

Te-Ho Wu/National Yunlin University of Science and Technology Deren Li/China Iron and Steel Research Institute Group Yasushi Takemura/Yokohama National University Cheol Gi Kim/DGIST

BP-01 Field-free magnetization switching by current-induced torque with antiferromagnetic/ferromagnetic structure Ming-Han Tsai, Kuo-Feng Huang, Ding-Shuo Wang, and Chih-Huang Lai Department of Material Science Engineering, National Tsing Hua University, Hsinchu, Taiwan BP-02 Thermal stability of CoFeB-MgO free layer with perpendicular anisotropy in different size of devices Hung-Yi Tsai, Chun-Liang Yang , Chih-Huang Lai Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan BP-03 Spin-orbital torque induced by Baron impurities in Platinum Bo-yuan Yang, and Chih-Huang Lai Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan BP-04 Effects of interfacial exchange interaction on the antiferromagnet-induced perpendicular magnetic anisotropy M. S. Tsai(a),P. H. Lin(a),C. W. Shih(a),M.J. Lee(a),C. W. Huang(a), N. Y.Jih(b), D. H. Wei(c), and B. Y. Wang(a),* (a)Department of Physics, National Changhua University of Education, Changhua , Taiwan

(b)The Center of Teacher Education, National Chung Hsing University, Taichung, Taiwan (c)National Synchrotron Radiation Research Center, Hsinchu, Taiwan BP-05 Magnetic proximity effects on antiferromagnet-induced perpendicular magnetic anisotropy in Ni/Co/Mn/Co/Cu(100) films C. W. Huang(a), M. S. Tsai(a), P. H. Lin(a), D. H. Wei(b), and B. Y. Wang(a)* (a)Department of Physics, National Changhua University of Education, Changhua, Taiwan (b) National Synchrotron Radiation Research Center, Hsinchu, Taiwan BP-06 Perpendicular magnetization of FeCo thin film deposited on Cu (001) by alternate monatomic layer deposition (a)J. Ochiai, (a)M. Tomita, (b)T. Ohkochi, (c)T. Miyamachi, (c)F. Komori,(a)M. Kotsugi (a)Tokyo University of Science, Tokyo 125-8585, Japan (b)SPring-8/JASRI, Hyogo 679-5198, Japan (c)ISSP, Chiba 277-0882, Japan

A-6

BP-07 Influence of Film Thickness on the Structure and Magnetic Properties of FePt and CoPt Films Formed on MgO(001) Substrate Masahiro Nakamura(a), Ryoma Ochiai(a), Mitsuru Ohtake(a,b), Masaaki Futamoto(a), Fumiyoshi Kirino(c), and Nobuyuki Inaba(d) (a)Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan (b)Faculty of Engineering, Kogakuin University, Tokyo 192-0015, Japan (c)Graduate School of Fine Arts, Tokyo University of the Arts, Tokyo 110-8714, Japan (d)Faculty of Engineering, Yamagata University, Yamagata 992-8510, Japan BP-08 Improvement in the resistive switching properties and magnetic of Ag/HfO2/p-type Si film device by doping cobalt Shin Ru Chiou* , Yu Min Hu and Huang Wei Chang Department of Applied Physics, National University of Kaohsiung 81148, Taiwan, R.O.C. BP-09 Garnet films fabricated by metal organic decomposition method on glass substrates and Gd3Ga5O12 substrates Hina Saito(a), Yoshito Ashizawa(b), and Katsuji Nakagawa(b) (a)Graduate School of Science and Technology, Nihon University, Chiba, Japan

(b)College of Science and Technology, Nihon University, Chiba, Japan BP-10 Study of a 4.5-T Wavelength Shifter Prototype with a Cryogenic PrFeB Permanent Magnet Chao-Chin Wang(a) (b), Cheng-Hsiang Chang (b), Hui-Huang Chen(b) Ching-Shiang Hwang(b), Chih-Hao Lee(a) (a)Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan (b)National Synchrotron Radiation Research Center, Hsinchu, Taiwan

BP-11 Magnetically driven dynamics of bio-functionalized beads via on-chip micromagnets Xinghao Hu, Byeonghwa Lim, Sandhya Rani Goudu, Eunjoo Jeong, Sri Ramulu Torati, CheolGi Kim

Department of Emerging Materials Science, DGIST, Daegu, 711-873, Republic of Korea BP-12 Detection of magnetic circular dichroism in amorphous materials utilizing a single-crystalline overlayer P. L. Ho(a), J. Lin(a), X. Y. Zhong(a), C. Song(b), J. Rusz(c), H. L. Xin(d), B. Cui(b), V. Kocevski(c,e), L. L. Han(d), R. Q. Lin(d) and J. Zhu(a)

(a)National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.(b)Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.(c)Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala S-75120, Sweden.(d)Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.(e)Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA. BP-13 Carrier role of superparamagnetic particles and beads in digital magnetophoretic circuits for living cell control Sandhya Rani Goudu, Byeonghwa Lim, Xinghao Hu, CheolGi Kim DGIST, Korea

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Poster Session PA Magnetic Thin Films and Nanostructures

Monday Afternoon, Aug. 1st, 2016 Room: Multifunction Room Chair: Tai-Chun Han/ National University of Kaohsiung

PA-01 Cell manipulation using magnetic honeycomb structure Chen-Yu Huang(a), Yong-De Xu(b), Ching-Ming Lee(b), Te-Ho Wu(b), Ming-Shinn Hsu, * Zung-Hang Wei(a)* (c) (a)Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City, Taiwan (b)Graduate School of Materials Science, National Yunlin University of Science and Technology, Yunlin, Taiwan (c)Department of Obstetrics and Gynecology, Ching-Kuo Campus of Min-Sheng Hospital, Taoyuan, Taiwan PA-02 CPP-GMR effects of Co2Fe0.4Mn0.6Si/ L12-Ag-Mg/ Co2Fe0.4Mn0.6Si devices: Spacer layer thickness dependence Yusuke Ina*, Takahide Kubota**, and Koki Takanashi IMR, Tohoku University PA-03 Magnetic properties of microfabricated MnxGa circler dot arrays H. Makuta, Y. Takahashi, R. Sato, T. Shima, and M. Doi Department of Electronic Engineering, Tohoku Gakuin University, Tagajo 985-8537, Japan PA-04 Effect of microfabrication on the magnetic properties for Nd-Fe-B thin films with several cap layers A. Sugawara, H. Iwama, R. Kurosu, M. Doi, T. Shima Faculty of Engineering, Tohoku Gakuin University, Tagajo, Japan PA-05 Field-driven Domain Wall Motion in Ferromagnetic Nanowires with Bulk Dzyaloshinskii-Moriya Interaction Zhouzhou Sun and Fengjun Zhuo College of Physics, Optoelectronics and Energy，Soochow University, Suzhou, Jiangsu 215006, China

PA-06 Synthesis and magnetic characterization of NiO-Ni core-shell nanotube arrays Z.W. Zhang (a), T. Yu* (a), Y. Liu(b), Y. H. Xu (a), W. J. Li (c), X. F. Han(c) (a)College of Physical Science and Technology, Sichuan University, Chengdu 610064, China (b)Analytical & Testing Center, Sichuan University, Chengdu, 610064, China (c)Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China PA-07 Various properties of Fe-Co magnetic films prepared by PLD method A. Yamashita, M. Nakano, A. Kurosaki, T. Yanai, and H. Fukunaga Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan PA-08 NEXAFS investigations of C60 / 3d -transition metal interfaces Kun-Ta Lu, Pei-Yu Cheng, Yuet-Loy Chan, Yao-Jane Hsu, Chun-I Lu, Tzu-Hung Chuang and Der-Hsin Wei National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan PA-09 Effect of compositional modulation on the structure and magnetic properties for Mn-Al thin films N. Kumagai, H. Iwama, M. Doi, and T. Shima Department of Engineering, Tohoku Gakuin University, Tagajo, Japan PA-10 Structural and Magnetic Properties of FeCo thin films N. Inami(a), T. Ueno(b), T. Hasegawa(c), S. Ishio(c), and K. Ono(a) (a)Institute of Materials Structure Science, KEK, Tsukuba, 305-0801, Ibaraki, Japan (b)ESICMM, NIMS, Tsukuba, 305-0047, Ibaraki, Japan (c)School of Engineering, Akita University, 010-8502, Akita, Japan

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Poster Session PB Nanoparticles and Bio-magnetism

Monday Afternoon, Aug. 1st, 2016 Room: Multifunction Room Chair: Yuan-Ron Ma/ National Dong Hwa University PB-01 Intracellular nanoparticle-mediated hyperthermia of microscopic tumours Chen-Yu Huang(a), Ying-Chang Tsao(b), Kuo-Wei Chiu(a), Ching-Ming Lee(b), Te-Ho Wu(b), Ming-Shinn Hsu (c)*, Zung-Hang Wei(a)* (a)Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City, Taiwan (b)Graduate School of Materials Science, National Yunlin University of Science and Technology, Yunlin, Taiwan (c)Department of Obstetrics and Gynecology, Ching-Kuo Campus of Min-Sheng Hospital, Taoyuan, Taiwan PB -02 New approach for quantitative single-cell analysis of magnetic labelling efficacy Chen-Yu Huang, (a) Ying-Chang Tsao, (b) Kuo-Wei Chiu, (a) Ching-Ming Lee, (b) Te-Ho Wu, (b) Ming-Shinn Hsu, (c)* Zung-Hang Wei(a)* (a)Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City, Taiwan (b)Graduate School of Materials Science, National Yunlin University of Science and Technology, Yunlin, Taiwan (c)Department of Obstetrics and Gynecology, Ching-Kuo Campus of Min-Sheng Hospital, Taoyuan, Taiwan PB -03 Three-Dimensional Magnetic Nanoparticle Imaging Using Multiple Pickup Coils Y. Tsujita, M. Morishita, M. Muta, T. Sasayama, and K. Enpuku Department of Electrical Engineering, Kyushu University, Fukuoka, Japan PB -04 Highly Sensitive Liquid-Phase Immunoassays Using Improved Magnetization Process of Magnetic Markers K. Nakamura, M. Ura, Y. Takafuji, T. Sasayama, T. Yoshida, and K. Enpuku

Department of Electrical Engineering, Kyushu University, Fukuoka, Japan PB -05 Single-Sided Magnetic Particle Imaging Using Planar Gradient Coil and Electric Scanning of Field Free Point K. Yamamoto, K. Tanabe, Shi Bai, T. Sasayama, T. Yoshida, and K. Enpuku Department of Electrical Engineering, Kyushu University, Fukuoka, Japan PB -06 Modeling of the Retardance in Citric Acid Coated Ferrofluids Using Stepwise Regression Jing-Fung Lin(a), Jer-Jia Sheu(b) (a)Department of Innovative Design and Entrepreneurship Management, Far East University, No.49, Zhonghua Rd., Xinshi Dist., Tainan City 74448, Taiwan (b)Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, No. 1, Nan-Tai Street, Yungkang Dist., Tainan City 71005, Taiwan PB -07 Paramagnetic Ions Dy3+ Doped Ultrathin Shell of SiO2@Gd2O3 Nanoparticles as a Potent Agent for Magnetic Resonance Imaging J. C. Yin, C. R. Li and Y. Z. Shao* State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics ＆ Engineering, Sun Yat-sen University, Guangzhou, P. R.Chin PB -08 Influence of annealing temperature on structural and magnetic properties of LaMnO3 nanoparticles Pardi S. Tola(a), D. H. Kim(a), Chunli Liu(a), T. L. Phan(a), and B. W. Lee(a,b) (a) Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin, Gyeonggi 449-791, South Korea

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Poster Session PC Functional Magnetic Materials and others

Monday Afternoon, Aug. 1st, 2016 Room: Multifunction Room Chair: Tai-Chun Han/ National University of Kaohsiung

PC-01 Effects of Mg-doping on magnetic and dielectric properties of magnetoelectric GaFeO3 nanocrystals Yi-De Chung, Chun Yun, and Tai-Chun Han Department of Applied Physics, National University of Kaohsiung, Kaohsiung 81148, Taiwan PC -02 Observation of spin glass behaviour and large exchange bias in Mn-Ni-Co-Sn Heusler Alloy Jyoti Sharma and K. G. Suresh Department of Physics, Indian institute of Technology Bombay, Mumbai, India PC -03 Giant magnetocaloric effect in manganite perovskites La0.7Ca0.3Mn1-xCuxO3 T. A. Ho(a), T. L. Phan(b) and S. C. Yu(c), S. H. Lim(a) (a)Department of Materials Science and Engineering, Korea University, Seoul, 136-713, South Korea (b)Department of Physics, Hankuk University of Foreign Studies, Yongin 449-791, South Korea (c)Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea PC -04 Magnetostriction and magnetic domain structure in an Fe-Ga alloy single crystal grown by the Czochralski method S. Asano(a), S. Fujieda(a), T. Fukuda(b), K. Ishiyama(c) S. Suzuki(a) (a)Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan (b)Fukuda Crystal Laboratory, Sendai 989-3204, Japan (c)Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan

PC -05 The exchange effect of paired-electrons in superconductivity Ke-Chuan Weng(a) (b) and C. D. Hu(b) (a)Research Center for Applied Sciences, Academia Sinica, Taipei Taiwan 11529 (b)Department of Physics, National Taiwan University, Taipei, Taiwan 10617 PC -06 Magnetic properties of the ternary stannides Sm3Co4Sn13 and Tb3Co4Sn13 Chia-Nung Kuo, Chang-Miin Wang , Chin-Shan Lue Department of Physics, National Cheng Kung University, Taian, Taiwan PC -07 High Field X-ray Diffraction Measurements in Mn2Sb0.9Sn0.1 Taoto Wakamori(a), Yoshifuru Mitsui(a), Kohki Takahashi(b), Rie Y. Umetsu(b), Masahiko Hiroi(a), Keiichi Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan PC -08 Magnetic Response of hybrid ferromagnetic and antiferromagnetic core-shell nanostructures U. Khan, W. J. Li, N. Nairan, M. Irfan, C. H. Wan, K. Javed, D. W. Shi, and X. F. Han* Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China. PC-09 Single crystal synthesis and physical properties of Nd3Co4Sn13 C.W. Tseng, C.N. Kuo, H.F. Liu, C.M. Wang, C.S. Lue Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan

A-10

PC-10 Physical properties of skutterudite-related Yb3Co3Sn13 H. F. Liu(a)*, C. N. Kuo(a) (b), C. S. Lue(a) (b), and Y. K. Kuo(c) (a)Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (b)Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan (c)Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan PC-11 The abnormal corrosion behavior of the (Nd,Ce)-Fe-B magnet with dual main phases in Nd2SO4 and NaCl solutions Xiaoning Shi, Minggang Zhu, Yaping Wu, Liwei Song, and Wei Li Division of Functional Material, Central Iron & Steel Research Institute, Beijing 100081, P.R.China

PC-12 Correlation between resistance state and saturation magnetization in (In, Co)-codoped ZnO thin film S. S. Li(a), Y. K. Su(a,b,c) and Y. M. Hu(d) (a)Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan (b)Institute of Microelectronics, Department of Electrical Engineering, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (c Department of Electrical Engineering, Kun Shan University, Tainan 710, Taiwan (d)Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan

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2nd August, Tuesday

A-12

Chair: Ko-Wei Lin / National Chung Hsing University

Advances in characterization of magnetic materials with polarized X-rays Peter Fischer

Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA

Physics Department, University of California, Santa Cruz, CA 94056, USA

email: PJFischer@lbl.gov

Nanomagnetism research aims to understand and control magnetic properties and behavior on

the nanoscale through proximity and confinement. A wealth of information has been achieved in this reductionists approach, which to a large extent was made possible by the development of advanced instrumentation targeting the nanoscale. However, it has been recognized, that the next step beyond the nanoscale will be governed by mesoscale phenomena [1], since those are supposed to add complexity and functionality, which are essential parameters to meet future challenges specifically in magnetic technologies in terms of speed, size and energy efficiency of spin driven devices. Advances in the development and application of multidimensional visualization techniques, such as tomographic magnetic imaging, and investigations of fast and ultrafast spin dynamics down to fundamental magnetic length and time scales with elemental sensitivity in emerging multi-component materials will be crucial to meet current and future goals in advanced magnetism research.

X-ray based spectro-microscopies offer a unique combination of both, diffraction limited spatial resolution in the nm regime, and temporal resolution across many scales dictated by the inherent time structures of x-ray sources, extending from fsec at X-ray lasers to the nsec regime at conventional storage rings. The polarization dependence of the x-ray interaction with magnetic materials, which is manifested in x-ray circular dichroism effects, provides quantitative and inherently element- and chemical sensitivity allowing to map e.g. the local distribution of spin and orbital magnetic moments [2].

I will review recent achievements and future opportunities with magnetic x-ray spectro-microscopies. Examples will include the dynamics of magnetic vortex and skyrmion textures [3,4,5] with potential application to novel magnetic logic elements [6,7], magnetic spectromicroscopy of domain walls [8] with soft x-ray ptychography [9], and approaches to image the 3dim magnetic domain structures in rolled-up thin films with x-ray tomography [9].

This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the U.S. Department of Energy Contract No. DE-AC02-05-CH1123 in the Non-Equilibrium Magnetic Materials Program. [1] R. Service, Science 335, (2012) p. 1167 [2] P. Fischer, and H. Ohldag, Report on Progress in Physics 78 (2015) p 094501 [3] S. Woo, K. Litzius, B. Krüger, M.-Y. Im, L. Caretta, K. Ritchter, M. Mann, A. Krone, R. Reeve, M. Weigand, P. Agrawal, P. Fischer, M. Kläui, G.S.D. Beach, Nature Materials (2016) published online 29 Feb 2016 [4] M.-Y.Im, K.-S. Lee, A.Vogel, J.-I. Hong, G. Meier, P. Fischer, Nature Communication 5 (2014) p. 5620 [5] H. Jung, Y.-S. Choi, K.-S. Lee, D.-S. Han, Y.-S. Yu, M.-Y. Im, P. Fischer, S.-K. Kim, ACS Nano 6 (2012) p. 3712 [6] M.J. Robertson, Ch.J. Agostino, A.T. N’Diaye, G. Chen, M.-Y. Im, P. Fischer, J Appl Phys 117 (2015) p. 17D145 [7] X. Shi, P. Fischer, V. Neu, D. Elefant, J. C.T. Lee, D. A. Shapiro, M. Farmand, T. Tyliszczak, H.-W. Shiu, S. Marchesini, S. Roy, S. D. Kevan, Applied Physics Letters 108, 094103 (2016) [8] R. Streubel, F. Kronast, P. Fischer, D. Parkinson, O.G. Schmidt, D. Makarov, Nature Communication 6 (2015) p. 7612

Plenary Talk 2 Peter Fischer

08:45-09:30, Tuesday, Aug. 2nd, 2016 Room: 1st Lecture Hall

A-13

Session BA Magnetic Thin Films and Nanostructures I

Tuesday Morning, Aug. 2nd, 2016 Room: 3rd Lecture Hall Chair: Hao Ouyang/ National Tsing Hua University

Daichi Chiba/ University of Tokyo

09:30-10:00 (Invited) BA-01 Magnetic Anisotropy Mechanisms of LTP MnBi and L10 Mn(Al,Ga) Thin Films Takao Suzukia,b,c aCenter for Materials for Information Technology (MINT), bDepartment of Electrical and Computer Engineering, cDepartment of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA 10:00-10:30 (Invited) BA-02 Electric field effect on magnetic properties in metallic ultra-thin films Daichi Chiba Department of Applied Physics, The University of Tokyo, 113-8656, Tokyo, Japan 10:30-11:00 (Invited) BA-03 Ultrafast magnetisation dynamics: pump-probe spectroscopy in the sub -10 fs range D. S. Schmool(a, b), C. S. Gonçalves(b), A. S. Vieira(b), D. Navas(b), M. Miranda(c), F. Silva(b), H. Crespo(b) (a)Laboratoire PROMES, CNRS (UPR 8521), Université de Perpignan Via Domitia, Perpignan, France (b)Departamento de Física e Astronomia, IFIMUP, Faculdade de Ciências, Universidade do Porto, Porto, Portugal (c)Department of Physics, Lund University, Lund, Sweden 11:00-11:30 (Invited) BA-04 Growth of L10 Phase in Epitaxial Magnetic Thin Films M. Futamoto(a), M. Nakamura(a), M. Ohtake(a), T. Shimotsu(b) (a)Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan (b)Hitachi Power Solutions, Hitachi-Naka, Ibaraki, Japan

11:30-11:45 BA-05 Structure and Magnetic Properties of SmCo5, GdCo5, and YCo5 Ordered Alloy Films Formed on Cr(100) and (211) Underlayers Mitsuru Ohtake(a,b), Yusuke Hotta(b), Makoto Yamada(b), Ataru Suzuki(b),Masaaki Futamoto(b), Fumiyoshi Kirino(c), and Nobuyuki Inaba(d) (a)Faculty of Engineering, Kogakuin University, Tokyo 192-0015, Japan (b)Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan (c)Graduate School of Fine Arts, Tokyo University of the Arts, Tokyo 110-8714, Japan (d)Faculty of Engineering, Yamagata University, Yonezawa 992-8510, Japan 11:45-12:00 BA-06 Resistive switching and magnetism modulation in oxide thin films Yuanmin Du, Chih-Huang Lai Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C.

A-14

Session BB Magnetic Recording II

Tuesday Morning, Aug. 2nd, 2016 Room: 1st Lecture Hall Chair: David Kuo/ Seagate Fremont

Hiroyuki Awano/ Toyota Technological Institute

09:30-10:00 (Invited) BB-01 Microwave-assisted magnetization reversal in perpendicular media using obliquely applied magnetic fields Y. Nozaki(a), S. Kasai(b) (a) Department of Physics, Keio University, Yokohama 223-8522, Japan (b) National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan 10:00-10:30 (Invited) BB-02 Heated Dot Magnetic Recording Media – Path to 10 Tdots/in2 David S. Kuoa, Kim Y. Leea, XiaoMin Yanga, Shuaigang Xiaoa, Yautzong Hsua, Zhaoning Yua, Michael Feldbaum1, Tim Klemmer1, Yukiko Kubotaa, Jan-Ulrich Thielea, Philip Steinera, Koichi Wagoa, Stefano Dallortob,c, and Deirdre Olynickb (a)Seagate Media Research, Fremont, California, USA (b)Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, California, USA (c)Oxford Instruments, Concord, Massachusetts, USA

10:30-11:00 (Invited) BB-03 Multiple layer magnetic recording using MAMR Simon J. Greaves(a), Yasushi Kanai(b) and Hiroaki Muraoka(a) (a)RIEC, Tohoku University, Sendai, Japan

(b)IEE, Niigata Institute of Technology, Kashiwazaki, Japan 11:00-11:30 (Invited) BB-04 FePt-C granular film for heat assisted magnetic recording Y.K. Takahashi, J. Wang, H. Pandey, A. Perumal, H. Sepehri-Amin, K. Hono National Institute for Materials science, Tsukuba, Japan

A-15

Session BC Magnetic Material Applications (sensors, motors, RF devices)

Tuesday Morning, Aug. 2nd, 2016 Room: 2nd Lecture Hall Chair: S. M. Yang/ National Taipei University of Technology

Min-Fu Hsieh/ National Cheng Kung University

09:30-10:00 (Invited) BC-01 Fundamental-mode orthogonal fluxgate: A platform for versatile magnetic measurement applications Ichiro Sasada Dept. Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580, Japan 10:00-10:30 (Invited) BC-02 On-chip Magnetic Thin-Film Noise Suppressor to Countermeasure Digital Noise from Switching Power Electronic Equipment Masahiro Yamaguchi(a)(b), Satoshi Tanaka(b), Jingyan Ma(a), Yasunori Miyazawa(b), Makoto Nagata(c), Koichi Kondo(d), Yasuyuki Okiyoneda(e), Masahiro Nishizawa(b) (a)Dept of Electrical Engng., School of Engng., Tohoku Univ., Sendai, Miyagi, Japan (b)New Industry Creation Hatchery Center, Tohoku Univ., Sendai, Miyagi, Japan (c)Graduate School of System Informatics, Kobe Univ., Kobe, Hyogo, Japan (d) NEC TOKIN Corporation, Sendai, Miyagi, Japan (e) Showa Aircraft Industry Co., Ltd., Akishima, Tokyo, Japann 10:30-11:00 (Invited) BC-03 Monolithic Three-Axis Fluxgate Magnetometer Jen-Tzong Jeng(a), Chih-Cheng Lu(b), Cheng-Yao Shiue(b), Van Su Luong(a) (a)Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan (b)Institute of Mechatronics Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

11:00-11:30 (Invited) BC-04 Tuning magnetic nanostructures of free layers for magnetoresistive sensors Yen-Fu Liu, Xiaolu Yin, Yi Yang and Sy-Hwang Liou Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Nebraska, USA

A-16

Poster Session PD Fundamental Properties & Computational Magnetism

Tuesday Morning, Aug. 2nd, 2016 Room: Multifunction Room Chair: Jui-Che Huang/ National Synchrotron Radiation Research Center PD-01 A first-principles study on the magnetic properties of Sc, V, Cr and Mn-doped monolayer TiS3 Huiling Zheng and Yu Yan Department of Physics, Jilin University, Changchun 130012, China PD-02 Magnetic Properties of MnCo1-xFexGe (0 ≤ x ≤ 0.12) M. Onoue(a), K. Ozono(a), Y. Mitsui(a), M. Hiroi(a), R. Y. Umetsu(b), K. Takahashi(b), Y. Uwatoko(c), K. Koyama(a) (a)Graduate School of Sci. & Eng., Kagoshima Univ., Kagoshima, 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan (c)Institute for Solid State Physics, The Univ. of Tokyo, Kashiwa, 277-8581, Japan PD-03 Magnetic and Structural Properties of Mn1.9Fe0.1Sb0.9Sn0.1 under Magnetic Fields A. N. Nwodo(a), R. Kobayashi(a), T. Wakamori(a), Y. Mitsui(a), M. Hiroi(a), K. Takahashi(b), Y. Uwatoko(c), Keiichi Koyama(a) (a)Graduate School of Sci. & Eng., Kagoshima Univ., Kagoshima, 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan (c)Institute for Solid State Physics, The Univ. of Tokyo, Kashiwa, 277-8581, Japan PD-04 Magnetic Fields Effect on Phase Formation of Ferromagnetic MnBi Synthesized by Reactive Sintering Daiki Miyazaki(a), Yoshifuru Mitsui(a), Kohki Takahashi(b), Keiichi Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University,890-8865, Kagoshima, Japan (b) Institute for Materials Research, Tohoku University, 980-8566, Sendai, Japan

PD-05 Pressure Effect on Weak Itinerant Electron Ferromagnet Ni3Al S. Yoshinaga(a), T. Kanomata(b), Y. Mitsui(a), K. Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University, Kagoshima, Japan (b)Research institute for Engineering and Technology, Tohoku-Gakuin University, Tagajyo, Japan PD-06 Magnetic Field-Induced L10-Ferromagnetic MnAl R. Kobayashi(a), Y. Mitsui (a), R. Y. Umetsu(b), K. Takahashi(b), M. Mizuguchi(b), K. Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University, Kagoshima Japan (b)Institute for Materials Research, Tohoku University, Sendai, Japan PD-07 Magnetic Field Effects on the Morphology of Bi-Mn System A. Takaki(a), Y. Mitsui(a), D. Miyazaki(a), R. Y. Umetsu(b), K. Takahashi(b), K. Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan PD-08 Nonlinear Temperature Characteristics in Magnetic Nanoparticles due to Hysteresis-Generated Heat J. W. Yu(a), B. C. Chen (b), C. Y. Ho (a), M. Y. Wen(c) (a)Department of Mechanical Engineering, Hwa Hsia University of Technology, Taipei 235, Taiwan (b Department of Chinese medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi 622, Taiwan (c)Department of Mechanical Engineering, Cheng Shiu University, Kaohsiung 833, Taiwan

A-17

Poster Session PE Spintronics Materials and Devices

Tuesday Morning, Aug. 2nd, 2016 Room: Multifunction Room Chair: Eric Chang/ Seagate Fremont PE-01 Spin polarization and magnetization of Heusler alloys Co2TiGa1−xSnx (x = 1.0, 0.5) R. Ooka(a), Y. Sukino(a), Y. Fujimoto(a), I. Shigeta(a), R. Y. Umetsu(b), A. Nomura(b), T. Yamauchi(c), T. Kanomata(d), K. Yubuta(c), M. Hiroi(a) (a)Grad. Sch. of Sci. and Eng., Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan (c)Institute for Solid State Physics, University of Tokyo, Chiba 277-8581, Japan (d) Grad. Sch. of Eng., Tohoku Gakuin University, Tagajo 890-8511, Japan PE-02 Nano-oxide layer induced magnetic property of IrMn-based spin-valve field sensors Manish Kumar Srivastava(a), Kuo-Feng Huang(b), Hsin-Hung Huang(c), Rex Weng(c), W. F. Pong(a) and Chih-Huang Lai(b) (a)Department of Physics, Tamkang University, Tamsui, Taiwan (b)Department of Materials Science and Engineering, NTHU, Hsinchu, Taiwan (c)Sensortek Technology Corporation, Hsinchu County 302, Taiwan PE-03 Separation of spin Seebeck effect and anomalous Nernst effect H. Wu, C. H. Wan, Z. H. Yuan, X. Zhang, and X. F. Han* Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, Chin PE-04 Magnetic domain wall motion in Co/Ni nanowires induced by a sloped electric field K. Yamada, S. Murayama, and Y. Nakatani Graduate school of Informatics and Engineering, University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan

PE-05 Excitation of magnetic domain wall velocity in (Co/Ni) nanowires induced by blocking the motion of vertical Bloch lines K. Yamada, and Y. Nakatani Graduate school of Informatics and Engineering, University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan PE-06 Examination of stability of skyrmions structure in Co/Ni multilayer films S. Hozumi, K. Yamada, and Y. Nakatani Graduate school of Informatics and Engineering, University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan PE-07 Polarization-Mediated Thermal Stability of CoFeB/BiFeO3 Heterointerface Qintong Zhang(a), Lu You(b), Xi Shen(a), Caihua Wan(a), Richeng Yu(a), Junling Wang(b), and Xiufeng Han(a)* (a)Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (b)School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore PE-08 Spin Current Tunneling through an Al2O3 Oxidation Barrier Investigated by Spin Pumping Eect Kuan-Chia Chiu(a), Wen-Che Chang(a), Jhen-Yong Hong(a), M. Sanjoy Singh(a), Gaun-Yu Luo(b), Jauyin-Grace Lin(b) and Minn-Tsong Lin(a), (c), (d)* (a) Department of Physics, National Taiwan University, Taipei 106, Taiwan (b)Center for Condensed Matter Sciences, Taipei 106, Taiwan (c)Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (d) Research Center for Applied Science, Academia Sinica, Taipei 106, Taiwan

A-18

PE-09 Spin-related effects in Heavy Metal/Ferromagnet/Antiferromagnet Layer Structure C. Engel, S. Goolaup, W. S. Lew School of Physical and Mathematical Sciences, Nanyang Technological, University, 21 Nanyang Link, Singapore 637371 PE-10 Electric field effect on magnetoresistance of multiferroic heterostructures Tomoyasu Taniyama, Junpei Okada, Mitsuru Itoh Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan

A-19

Poster Session PF Functional Magnetic Materials and others

Tuesday Morning, Aug. 2nd, 2016 Room: Multifunction Room Chair: Jun-Yang Lai/ National Pingtung University of Education PF-01 Synthesis and high-frequency absorption property of flower-like nickel-ferrite composites Guangqiang Zhanga(a), Hangrong Dongb(b), Shaoxiong Zhoua(a), Min Zeng*(b). (a)Advanced Technology & Materials Co., Ltd., China Iron & Steel Research Institute Group Co., Ltd., Beijing 100081, China (b)School of Materials Science and Engineering, Beihang University, Beijing 100191, PR China PF-02 First to Second Order Phase Transformation in La0.7-xSmxCa0.3MnO3 Compounds Tran Dang Thanh(a), Dinh Chi Linh(b), Tien Van Manh(a), Le Viet Bau(c), and Seong Cho Yu(a) (a)Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea (b)Institute of Materials Science, Vietnam Academy of Science and Technology, Hanoi, Vietnam (c)Department of Engineering and Technology, Hong Duc University, Thanh Hoa, Vietnam PF-03 Magnetoresistance and Magnetocaloric Effects in La0.7Ca0.3Mn0.9Co0.1O3 Exhibiting the Crossover of First- and Second-Order Phase Transitions Tran Dang Thanh(a), Duong Anh Tuan(b), The Long Phan(c), and Seong Cho Yu(a) (a)Department of Physic, Chungbuk National University, Cheongju 361-763, South Korea (b)Department of Physics, University of Ulsan, Ulsan 680-749, Korea (c)Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791, South Korea

PF-04 The universal behavior in ternary equiatomic RETAl (RE = Er and Ho, T = Fe and Ag) compounds Yikun Zhang (a), (b), *, Xi Li (a), Zhongming Ren (a), Gerhard Wilde(b) (a)State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China (b)Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Straße 10, D-48149 Münster, Germany PF-05 Collective Magnetoresistance Effect of Ferromagnetic Microparticle Suspension G. Jia(a,c), H.-G. Piao(a,b)*, D.-H. Kim(b), and S.-C. Yu(b) (a)CTGU Collaborative Innovation Center for Magneto-electronic Industry, College of Science, China Three Gorges University, Yichang 443002, China (b)Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea (c)College of Electrical Engineering & New Energy, China Three Gorges University, Yichang 443002, China PF-06 Photo-enhanced ferromagnetism in high K+-containing K-Ni-Cr Prussian blue analogues coated on Rb-Co-Fe nanocubes Chi-Hung Lee,(a) Min-Yung Wang,(a) Erdembayalag Batisakhan,(a) Chun-Ming Wu,(b) Chin-Wei Wang,(b) and Wen-Hsien Lia,*(a) (a)Department of Physics, National Central University, Jhongli 32001, Taiwan (b)Neutron Group, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan

A-20

PF-07 Additive Manufacturing of Cobalt-based Organic Ferromagnetic Materials Junfeng Huang(a), Winco K.C. Yung(a), Zhengong Meng(b), Desmond T.C. Ang(a), Hang Shan Choy(a), Guijun Li(a) (a)Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong (b)Department of Chemistry, Hong Kong Baptist University, Hong Kong PF-08 Current induced skyrmion dynamics via spin orbit coupling types Seung-Jae Lee(a), Kyung-Jin Lee(a), (b) (a)KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea (b)Department of Materials Science and Engineering, Korea University, Seoul Korea PF-09 Detrimental Effect of Interfacial Dzyaloshinskii-Moriya Interaction on Perpendicular Spin-Transfer-Torque Magnetic Random Access Memory Ik Sun Hong(a), Peong Hwa Jang(b), K.-J. Lee(a),(b) (a)KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-713, Korea (b)Department of Materials Science and Engineering, Korea University, Seoul 136-713, Korea

PF-10 Excitation Properties of Surface Plasmon of Non-Solid-Solution Ag-(Co, Fe) Thin Films Yusuke Tada(a), Toru Tachikawa(a) , Yoshito Ashizawa(b), and Katsuji Nakagawa(b) (a)Graduate School of Science and Technology, Nihon University, Chiba, Japan. (b College of Science and Technology, Nihon University, Chiba, Japan. PF-11 Substitution-modified optical and magnetic properties of La doped BaTi0.9Fe0.1O3 D. H. Kim, Pardi S. Tola, and B. W. Lee* Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin, Gyeonggi 449-791, South Korea PF-12 Ab Initio Studies of Structure, Electronic and Optical Properties of Sn-doped Hematite Taewon Min, Jaekwang Lee* Department of Physics, Pusan National University, Busan, 46241, Republic of Korea

A-21

Plenary Talk 3 Robert D. Shull

13:30-14:15, Tuesday, Aug. 2nd, 2016 Room: 1st Lecture Hall Chair: Jong-Ching Wu/ National Changhua University of Education Application of the Magneto-Optic Indicator Film Technique to Reveal

Domain Dynamics in Thin-Film Magnetic Materials R.D. Shull(a), V.S. Gornakov(b), V.I. Nikitenko(a,b)

(a) National Institute of Standards and Technology, Materials Science and Engineering Division, Gaithersburg, MD, USA

(b)Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, Russia

e-mail: shull@nist.gov

The manner in which a material reverses its magnetization when subjected to a reversed magnetic field dictates the usefulness of that material for different applications. The best way to determine this is to view a sequence of domain images as the reversal occurs. One technique which does enable such real-time observations is the magneto-optic indicator film (MOIF) method [1] wherein an in-plane magnetized film with a large Faraday Effect is placed on top of the sample of interest. The flux leakage from the sample at a domain wall will locally rotate the imaging film’s magnetization vector out of the film plane so when a polarized light beam goes through the imaging film, it’s polarization vector rotates differently where the imaging film is magnetized out of the plane compared to where it is in-plane magnetized. The result is a picture of the domain walls in the sample, even in samples as thin as 2 nm. And from the contrast at two different walls of a domain, the direction of magnetization in that domain can be determined. Movement of domain walls induced by the application of a magnetic field can then be viewed in real time in the imaging film. Here, we review reversal in simple ferromagnets [2], exchange-biased materials [3], exchange-spring films [4], and in shaped micrometer-sized elements [5] using the MOIF technique.

[1] L.H. Bennett, R.D. McMichael, L.J. Swartzendruber, S. Hua, D.S. Lashmore, A.J. Shapiro, V.S. Gornakov, and V.I. Nikitenko, Appl. Phys. Lett. 66, 888 (1995). [2] A.J. Shapiro, V.S. Gornakov, V.I. Nikitenko, R.D. McMichael, W.F. Egelhoff, Y.W. Tahk, R.D. Shull, and Li Gan, JMMM 240, 70 (2002). [3] V.I. Nikitenko, V.S. Gornakov, L.M. Dedukh, Yu.P. Kabanov, A.F. Khapikov, A.J. Shapiro, R.D. Shull, A. Chaiken, E.P. Michel, Phys. Rev. B 57, No. 14, R8111 (1998). [4] J. Jiang, E. Fullerton, C. Sowers, I. Inomata, S. Bader, A. Shapiro, R. Shull, V. Gornakov, V. Nikitenko, IEEE Trans. Magnetics 35, 3229 (1999). [5] R.D. Shull, Yu.P. Kabanov, V.S. Gornakov, P.J. Chen, and V.I. Nikitenko, JMMM 400, 191 (2016).

A-22

Session CA Soft/Hard Magnetic Materials I

Tuesday Afternoon, Aug. 2nd, 2016 Room: 3rd Lecture Hall Chair: Wen- Cheng Chang/ National Chung Cheng University

Michael Coey/ Trinity College

14:15-14:45 (Invited) CA-01 Magnetic Anisotropy - How much is enough for a permanent magnet? J. M. D. Coey School of Physics and CRANN, Trinity College, Dublin 2, Ireland 14:45-15:15 (Invited) CA-02 Optimization of the magnetic properties of hot deformation NdFeB magnets Y. I. Lee(a), S. T. Chang(a), G. Y. Huang(a), C. W. Shih(a), W. C. Chang(a), H. W. Chang(b) and Y. J. Chen(c) (a)Department of Physics, National Chung Cheng University, Chia-Yi, 621 Taiwan. (b)Department of Physics, Tunghai University, Taichung, 407 Taiwan. (c)Metal Industries Research & Development Center, Kaohsiung, 81160, Taiwan.

15:15-15:45 (Invited) CA-03 High-Aspect-Ratio magnetic nanoparticles for Future Permanent Magnets J.P. Liu Department of Physics, University of Texas at Arlington

A-23

Session CB Spintronic Materials & Devices II

Tuesday Afternoon, Aug. 2nd, 2016 Room: 1st Lecture Hall Chair: Yuan-Chieh Tseng/ National Chiao Tung University

Eiji Saitoh/ Tohoku University

14:15-14:45 (Invited) CB-01 Spin Current Generators Eiji Saitoha-d aERATO-SQR, JST, Japan bWPI-AIMR, Tohoku University, Japan cInstitute for Materials Research, Tohoku University, Japan dASRC, JAEA, Japan 14:45-15:15 (Invited) CB-02 Theory of magnetic insulator | metal bilayers Gerrit E.W. Bauer(a,b) (a)IMR, Tohoku University, Sendai, Japan (b)Kavli Institute of NanoScience, TU Delft, The Netherlands 15:15-15:45 (Invited) CB-03 Fully Functional 64Mb STT-MRAM Utilizing Advanced pMTJ on 300mm Wafers Yiming Huai*, E. Abedifard, J. Zhang, Y. Zhou, X. Wang, Z. Wang, X. Hao, D. Jung, K. Satoh, B. Yen, H. Gan, K. Moon, U. Chandrasekhar Avalanche Technology, 46600 Landing Pkwy, Fremont, CA 94538 15:45-16:15 (Invited) CB-04 Magnetic bubblecade memory based on chiral domain walls Kyoung-Woong Moon(a), Duck-Ho Kim(b), Sang-Cheol Yoo(b),(c), Soong-Geun Je(b), Byong Sun Chun(a), Wondong Kim(a), Byoung-Chul Min(c), Chanyong Hwang(a) & Sug-Bong Choe(b) (a)Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea. (b)CSO and Department of Physics, Seoul National University, Seoul 151-742, Republic of Korea.

(c)Spin Convergence Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea 16:15-16:45 (Invited) CB-05 Grand design of novel spintronic and electronic materials for next generation spintronics and electronics Xiaolin Wang* Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Australia 16:45-17:00 CB-06 Study of Structural and Magnetism of Praseodymium- doped CeO2 Nanoparticles William Lee(a), Shih-Yun Chen(a), Cheng-Wei Ku(a), Jun-Han Chen(b), Hsiang-Lin Liu(b) (a)Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan (b)Department of Physics, National Taiwan Normal University, Taipei, Taiwan 17:00-17:15 CB-07 Study on giant spin-orbit torque in perpendicular magnetization Pd/CoFeB structure P.C. Chen, Y. Du, C.H. Lai National Tsing Hua University, Hsin-chu, Taiwan

A-24

Session CC Applications of Quantum Beams in Cutting Edge Magnetism Research Tuesday Afternoon, Aug. 2nd, 2016 Room: 2nd Lecture Hall

Chair: Chih-Hao Lee/ National Tsing Hua University Frank Kloss/ BRAGG Institute

14:15-14:45 (Invited) CC-01 Opportunities for Neutron Scattering in Spintronic Thin Film Materials Science Frank Klosea,b, G. L. Causera,c, D. L. Cortiea

aAustralian Nuclear Science and Technology Organisation, Lucas Heights, Australia bThe City University of Hong Kong, China SAR cUniversity of Wollongong, Wollongong, Australia 14:45-15:15 (Invited) CC-02 Magnetic and structural phenomena underlying large magnetic-field- induced strains in a ferromagnetic Heusler Ni-Mn-Ga alloy A. Pramanick

Department of Physics and Materials Science, City University of Hong Kong, TatChee Avenue, Kowloon, Hong Kong 15:15-15:45 (Invited) CC-03 Complex magnetic phases and magnetic incommensurability in type-II multiferroic Co3TeO6 Wen-Hsien Lia, Chi-Hung Leea, Chin-Wei Wanga, Hung-Duen Yangb, Jeffrey W. Lynnc, and Helmuth Bergerd

aDepartment of Physics, National Central University, Jhongli 32001, Taiwan bDepartment of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan cNIST Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA dInstitute of Physics of Complex Matter, EPFL, Lausanne, Switzerland

15:45-16:15 (Invited) CC-04 Orbital ordering as the unifying mechanism for both the structural and antiferromagnetic transitions in the Fe-based superconductors Wei Bao Renmin University of China, Department of Physics 16:15-16:45 (Invited) CC-05 Study of the magnetism of the functional materials using neutron and x-ray scattering Chao-Hung Du Department of Physics, Tamkang University, Taiwan 16:15-16:45 (Invited) CC-06 Investigating magnetic and multiferroic oxide thin films with quantum beam techniques Sara J. Callori Department of Physics, California State University, San Bernardino, California, USA

A-25

Poster Session PG Magnetic Recording

Tuesday Afternoon, Aug. 2nd, 2016 Room: Multifunction Room Chair: An-Cheng Sun/ Yuan Ze University PG-01 Preparation and magnetic properties of perpendicular Co-rich Co-Pt films S. C. Chen (a), C. F. Lu(a), C. K. Wen(b), T. H. Chuang(b), S. T. Chen(b), P. C. Kuo(b) (a)Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei 24301, Taiwan. (b)Institute of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan. PG-02 Epitaxial Co80Pt20 films with columnar grains and perpendicular magnetic anisotropy at ambient temperature S. C. Chen(a), C. F. Lu(a), R. Z. Chen(b), C. M. Wang(c), P. C. Kuo(c) (a Department of Materials Engineering and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, Taipei 243, Taiwan. (b)New Materials R&D Dept., China Steel Corporation, Kaohsiung 812, Taiwan. (c)Institute of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan. PG-03 MAMR frequency selection on [CoX/Pt]4 media with different anisotropy orientation distribution Zhen Zhao, Jiangnan Li, Longze Wang, Dan Wei* Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 PG-04 Hc Angular Dependence of ECC Media for Ontrack and Crosstrack Performance Justin Hwu, Pin-Wei Huang*, Shifu Lee, and Weikang Shen Seagate Technology, Fremont, CA, USA

PG-05 CoPt-B2O3 granular media with high Ku and low intergranular exchange coupling Kim Kong Tham(a), Ryosuke Kushibiki(a), Shintaro Hinata(b), Shin Saito(b) (a)Tanaka Kikinzoku Kogyo K. K., 22, Wadai, Tsukuba, Ibaraki, 300-4247, Japan (b)Tohoku University, 6-6-05, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan PG-06 Stacking faults induced domain wall pinning in (001) FePd thin film Ching Hung Hsiao, Chuenhou (Hao) Ouyang Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan PG-07 Numerical analysis on cross-track characteristics for tracks recorded with microwave assistance T. Tanaka(a), D. Sakamoto(a), Y. Kanai(b) and K. Matsuyama(a) (a)ISEE, Kyushu University, Fukuoka, Japan (b)IEE, Niigata Institute of Technology, Kashiwazaki, Niigata, Japan PG-08 The non-local energy dissipation in All-Optical magnetization Switching of GdFeCo thin films Hiroki Yoshikawa(a), Souliman El Moussaoui(b), Shinnosuke Terashita(a), Ryohei Ueda(a), Arata Tsukamoto(b) (a)Graduate School of Science and Technology, Nihon University, Chiba, Japan (b)College of Science and Technology, Nihon University, Chiba, Japan PG-09 All-Optical magnetization Switching on multi level GdFeCo magnetic double layered film Shinnosuke Terashita(a), Hiroki Yoshikawa(a) and Arata Tsukamo(b) (a)Graduate School of Science and Technology, Nihon University, Funabashi, Japan. (b)College of Science and Technology, Nihon University, Funabashi, Japan.

A-26

Poster Session PH Magnetic Thin Films and Nanostructures

Tuesday Afternoon, Aug. 2nd, 2016 Room: Multifunction Room Chair: Lin- Jai Tsai/ National Chung Hsing University PH-01 Magnetic properties and spin dependent transport in Fe-filled carbon nanotubes Y. H. Xu, Z. W. Zhang, F. Boi, T. Yu* College of Physical Science and Technology, Sichuan University, Chengdu 610064, China PH-02 Construction of Pulse Laser Deposition System for fabrication of magnetic multilayers M. Kotsugi, M. Tomita, J. Ochiai Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo, Japan PH-03 Insertion Effect of Nonmagnetic Spacer in Co/FeMn Exchange Bias Films A. Yoshida, N. Hosoito Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Japan PH-04 Paramagnetic gadolinium-doped zinc oxide thin films grown under two different oxygen partial pressure Fang-Yuh Lo(a), Tsung-Chun Hsieh(a), Tzu-Lung Tseng(a), Xiu-Zhi Mi(a), Chih-Feng Chien(a), Yung-Yuan Hsu(a), and Ming-Yau Chern(b) (a)Department of Physics, National Taiwan Normal University, 11677 Taipei City, Taiwan (b)Department of Physics, National Taiwan University, 10617 Taipei City, Taiwan PH-05 Gate-voltage Controlled Tunneling Magnetoresistance in a Magnetic Tunneling Junction with an Inserted Thin Metallic Layer Sui-Pin Chen Department of Electrophysics, National Chiayi University, Chia Yi, Taiwan PH-06 Modulating permalloy thin films on grating structure for anisotropy magnetic sensor G. H. Lai, H. C. Han , J. C. Wu* Department of Physics, National Changhua University of education, Changhua 500, Taiwan

PH-07 Controlling of standing spin wave configuration in nanowires with domain wall X. Ya, T. Tanaka and K. Matsuyama Graduate School of ISEE, Kyushu University, Fukuoka 819-0395, Japan PH-08 Thermal Analysis of Superparamagnetic Nanoparticles Subject to an Alternating Magnetic Field C. Y. Ho (a), B. C. Chen(b), J. W. Yu(a) , M. Y. Wen(c) (a)Department of Mechanical Engineering, Hwa Hsia University of Technology, Taipei 235, Taiwan (b)Department of Chinese medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi 622, Taiwan (c)Department of Mechanical Engineering, Cheng Shiu University, Kaohsiung 833, Taiwan PH-09 Study of Change film thickness and bombarded voltage to affect structure and perpendicular exchange bias of SiO2 / CoO / [Co / Pt] 3 multilayer film C.-C. Chi, C.-H. Hsiao , Chuenhou (Hao) Ouyang , Den-Lo Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan

A-27

Poster Session PI Magnetic Materials Applications(sensors, motors, RF devices)

Tuesday Afternoon, Aug. 2nd, 2016 Room: Multifunction Room Chair: Chang-Chou Hwang/ Feng Chia University PI-01 Magnetic circuit design of an elliptically polarized undulator TingYi Chung, FuYuan Lin, ChengHsing Chang, JuiChe Huang, ChengHsiang Chang, JyhChyuan Jan, ChingShiang Hwang National Synchrotron Radiation Research Center, Hsinchu, Taiwan PI-02 Improvement of stress induced reliability shift in AMR sensor Zitu-Tin Lin (a), Wen-Jeng Lin (a) , Fu-Tai Liu (a) , and Yuan-Chieh Tseng (b) (a)Technology Division Voltafield Technology Corporation, Hsinchu, Taiwan (b)Materials Science & Engineering (MSE), National Chiao Tung University, Taiwan. PI-03 Magnetoimpedance characteristics on micromachined thin-film elements less than 100-micrometers length H. Kikuchi(a), T. Shima(a), H. Uetake(b), S. Yabukami(b) (a)Faculty of Enginnering, Iwate University, Morioka, Japan (b)Faculty of Enginnering, Tohoku-Gakuin University, Sendai, Japan PI-04 Barcode nanowires for multiplexed bioanalysis S. R. Torati, X. H. Hu, C. G. Kim Department of Emerging Materials Science, DGIST, Daegu, 42988, Korea. PI-05 The influence of Magnet block imperfections on field performance for in-vacuum undulators at NSRRC Chin-Kang Yang, Cheng-Ying Kuo, Yun-Liang Chu, Sei-Da Chen, Jui-Che Huang National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan PI-06 Magneto-Electronic Hydrogen Gas Sensors Grace L. Causer(a) (b), Mikhail Kostylev(c), Chris Lueng(c), Frank Klose(a) (a)Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia (b)University of Wollongong, Wollongong, Australia (c)University of Western Australia, Crawley,

Australia PI-07 Application of Tunnel Magnetoresistance Sensor in two-dimensional magnetic tracking Xuan-Thang Trinh(a), Jen-Tzong Jeng*(a), Van-Su Luong(a), Chih-Cheng Lu(b) (a)Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan (bInstitute of Mechatronics Engineering, National Taipei University of Technology, Taipei 10608, Taiwan PI-08 Synthesization of magnetic particle for adsorption of bovine serum albumin in microfluidic Yu-Chi Kuo, Yin-Chou Huang, Chao-Ming Su, Shyh-Liang Lou, Tzong-Rong Ger Department of Biomedical Engineering, Chung Yuan Christian University, Taoyuan, Taiwan PI-09 Principle of magnetic circuit design for a Particle Accelerator Undulator Jui-Che Huang, Chin-Kang Yang, Ching-Shiang Hwang National Synchrotron Radiation Research Centre, HsinChu Taiwan PI-10 Optimizing the magnetic properties of cascaded spin valve ellipses for magnetic field sensors Y. C. Su(a), K. W. Lee(a), Y. C. Lee(a), V. S. Luong(c), J. H. Hsu(b), J. T. Jeng(b), C. R. Chang(b), Jen-Tzong Jeng(c) and Jong-Ching Wu(a) (a)Department of Physics, National Changhua University of Education, Taiwan (b)Department of Physics, National Taiwan University, Taiwan (c)Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences PI-11 Special magnetic structure for cell sorting by novel 3D printing Ming Da Yanga,b*, Yu Ting Huanga, Mean Jue Tungb aIndustrial Technology Research Institute, Hisinchu, Taiwan, R.O.C bNational Tsing Hua University, Hisinchu, Taiwan, R.O.C

A-28

3rd August, Wednesday

A-29

Chair: Mean-Jue Tung / Industrial Technology Research Institute

Prospects for low field magnetic imaging agents

John Moreland

National Institute of Standards and Technology, Boulder, CO 80303, USA

There are new opportunities for the application of magnetic thin-film structures and

nanomaterials as smart tags for in-vivo medical imaging applications. Both microfabrication and

chemical synthesis methods have advanced to the point that is possible to mass produce magnetic

smart tags with specific geometries, materials, and unique gyromagnetic characteristics. The

possibilities for applications of magnetic smart tags is expanding given the immergence of ultra-low

field magnetic resonance imaging (ULF MRI) and magnetic particle imaging (MPI) as viable medical

imaging modalities. I will discuss some prospects for “fusing” magnetodynamic phenomena with

MRI and MPI.

Plenary Talk 4 John Moreland

08:45-09:30, Wednesday, Aug. 3rd, 2016 Room: 1st Lecture Hall

A-30

Session DA Nanoparticles and Related Applications

Wednesday Morning, Aug. 3rd, 2016 Room: 3rd Lecture Hall Chair: Yasushi Takemura/ Yokohama National University

Cheolgi Kim/ DGIST

09:30-10:00 (Invited) DA-01 Improved Liquid-Phase Detection of Biological Targets Based on Brownian Relaxation of Magnetic Markers K. Enpuku Department of Electrical Engineering, Kyushu University, Fukuoka, Japan. 10:00-10:30 (Invited) DA-02 Magnetization reversal of self-assembled one-dimensional chains of Fe3O4 nanoparticles Alexander Samardaka, Alexander Davydenkoa, Alexey Ogneva, Yoo Sang Jeonb, Young Soo Choib, Young Keun Kimb aSchool of Natural Sciences, Far Eastern Federal University, Vladivostok, Russia bDepartment of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea 10:30-11:00 (Invited) DA-03 Rotational hysteresis loss analysis for randomly oriented α”-Fe16N2 nanoparticles assembly Masahiro Tobise, Tomoyuki Ogawa and Shin Saito Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6–6–05 Aoba, Aramaki, Aoba–ku, Sendai 980–8579, Japan 11:00-11:15 DA-04 Core-Shell Magnetic Nanostructures with high Hyperthermia Capability Shuli He(a,b), Hongwang ZHANG(b), Xueyan Li(a), Yihao Liu(a) , Chen Liu(a) , Hao Zeng(a*) (a)Department of Physics, Capital Normal University, Beijing 100048, P. R. China (b)Department of Physics, University at Buffalo-SUNY, Buffalo, New York 14260, United States

11:15-11:30 DA-05 Finite size effect on magnetic transitions of La1-xSrxMnO3 nano-particles with x=0.1~0.4. Y. S. Chen, K. L. Liang and J. G. Lin* Center for Condensed Matter Sciences, National Taiwan University, Taiwan 11:30-11:45 DA-06 Preparation of Fe Nanoparticles by Submerged Arc Discharge Method Kuo-Hsiung Tseng (a), Mei-Jiun Chen(a), Chaur-Yang Chang(a), Meng-Yun Chung(a) (a) Department of Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan, R.O.C. 11:45-12:00 DA-07 ab initio calculations to study interfacial intermixing of core(-Fe2O3)/shell(CoO) nanoparticles and superexchange effect at interface C.-C. Chi (a), C.-H. Hsiao (a), E. Skoropata (b), J. van Lierop (b) , Chuenhou (Hao) Ouyang (a) (a) Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (b) Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada

A-31

Session DB Spin Torque Phenomena in Emergent Materials

Wednesday Morning, Aug. 3rd, 2016 Room: 1st Lecture Hall Chair: Ssu-Yen Huang/ National Taiwan University

Dustin A. Gilbert/ NIST Center for Neutron Research

09:30-10:00 (Invited) DB-01 Spin transport in magnetic heterostructures based on topological insulators J. Kwo,aY. T. Fanchiangb, C. N. Wua, H. Y. Lina, K. H. Chena, J. G. Linc, M. Hongb, andS. F. Leed aDepartment of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan bGraduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan cCenter for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan dInstitute of Physics, Academia Sinica, Taipei 115, Taiwan 10:00-10:30 (Invited) DB-02 Transport of spin waves and the interaction with domain walls in magnetic nanowires with perpendicular anisotropy Liang-Juan Changa, Jun-Zhi Liangb, Shang-Fan Leea* a Institute of Physics, Academia Sinica, Taipei 115, Taiwan bDepartment of Physics, Fu Jen Catholic University, Taipei 24205, Taiwan

10:30-11:00 (Invited) DB-03 Spintronics with small molecules M. Galbiati, S. Tatay, S. Delprat, C. Barraud, P. Seneor, R. Mattana and F. Petroff Unité Mixte de Physique CNRS/Thales, Palaiseau, France 11:00-11:30 (Invited) DB-04 Voltage-controlled magnetization switching in spintronic devices Wei-Gang Wang Department of Physics, University of Arizona, Tucson, Arizona 85721, USA 11:30-12:00 (Invited) DB-05 Thermal spin detection of inverse spin Hall effect by longitudinal spin Seebeck effect Ssu-Yen Huang Department of Physics, National Taiwan University, Taipei, Taiwan

A-32

Session DC Magnetic Recording III

Wednesday Morning, Aug. 3rd, 2016 Room: 2nd Lecture Hall Chair: Jyh-Shen Tsay/ National Taiwan Normal University

David S. Kuo/ Seagate Fremont

09:30-10:00 (Invited) DC-01Magnetic recording on the RE-TM /Pt magnetic wire deposited on nano-imprinted plastic substrate Hiroyuki Awano*, Satoshi Sumi, Yuichiro Kurokawa, Do Bang, Akihiko Moribayashi, Ryogo Yoshimura, and Tsukasa Asari Toyota Technological Institute, Nagoya, Aichi 468-8511, JAPAN 10:00-10:30 (Invited) DC-02 Ferromagnetic resonance for CoPt- based granular films with intergranular magnetic interaction Shin Saito(a), Shintaro Hinata(a), (b), Daiji Hasegawa(a) (a) Tohoku University, 6-6-05, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan (b) JSPS, Research Fellow (PD) 10:30-11:00 (Invited) DC-03 Microstructure and magnetic properties of FePt film with carbide intermediate layer Jai-Lin Tsai, Jie-Lin Tzeng, Keng-Chun Hu, Hsu-Kang Li, Zu-Yu Pan, Yuan-Shuo Chang, Chang-Chun Liao Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan

11:00-11:30 (Invited) DC-04 Altering coercivity via various growth rate on domain wall pinning (001) FePd thin film C. H. Hsiao, and Chuenhou (Hao) Ouyang Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan 11:30-11:45 DC-05 Microstructure and magnetic anisotropy of FePt thin film by rapid thermal annealing Jin-Yan Chiou and Chuenhou(Hao) Ouyang Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

A-33

Poster Session PJ Spintronics Materials and Devices

Wednesday Morning, Aug. 3rd, 2016 Room: Multifunction Room Chair: Yiming Huai/ Avalanche Technology

PJ-01 Characterization of the field-like term of spin-orbit torque in Ta/Co/Pt by sweeping transverse field Feilong Luo, Sarjoosing Goolaup, Sihua Li, Gerard Joseph Lim, Funan Tan, Christian Engel, Fusheng Ma, Wen Siang Lew

School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 PJ-02 Voltage-controlled magnetic anisotropy in an ultrathin Fe layer sandwiched between Cr and MgO layers Takayuki Nozaki(a), Anna Kozioł-Rachwał (a),(b), Witold Skowroński(a),(b), Vadym Zayets(a), Yoichi Shiota(a), Shingo Tamaru(a), Hitoshi Kubota(a), Akio Fukushima(a), Shinji Yuasa(a), and Yoshishige Suzuki(a), (c) (a)National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki, Japan (b)AGH University, Al. Mickiewicza 30, 30-059 Krakow, Poland (c) Osaka University, Toyonaka, Osaka, Japan PJ-03 Curvature induced spin accumulation Z.B. Siu(a), M.B.A. Jalil(a) and S.G. Tan(b) (a) National University of Singapore, Singapore (b) Data Storage Institute, Singapore PJ-04 Effective Hamiltonian for Topological Insulator Nanotubes Z.B. Siu(a), M.B.A. Jalil(a) and S.G. Tan(b)

(a) National University of Singapore, Singapore (b) Data Storage Institute, Singapore

PJ-05 Magnetic Phase Transition of La1-xSrxMnO3 Induced by Charge Transfer and Interdiffusion Angus Huang (a), Ching-Hao Chang (b)*, Horng-Tay Jeng(a), (c)** (a) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (b) Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrae 20 Dresden, 01069, Germany (c) Institute of Physics, Academia Sinica, Taipei 11529, Taiwan PJ-06 Controllable Synthesis of Porous Fe3O4 Nanospheres and Their Application to Electromagnetic Wave Absorption Rambabu Kuchi(a), Viet Dongquoc(b), Jong-Ryul Jeong(a) (b)* (a)(b) Department of Materials Science and Engineering, Graduate School of Energy Science and Technology, Chungnam National University, Daejeon 305-764, Korea PJ-07 Effect of co-doping on the magnetic and electronic properties of multiferroic Y1-

yDyyMn1-xFexO3 L.P. Yang(a), A.M. Zhang(a)#, Y. Dai(a), Z.R. Gao(a) and X.S. Wu(b) (a)College of Science, Hohai University, Nanjing 210098, China (b)National Laboratory of Solid State Microstructures & Department of Physics, Nanjing University, Nanjing 210093, China PJ-08 Periodic Gate Voltage on the Magnetic Tunneling Junction Sui-Pin Chen Department of Electrophysics, National Chiayi University, Chia Yi, Taiwan

A-34

PJ-09 Flip-Flop SR Latch and Half-Adder Logic Circuit Configurations using SOT-MTJ D.J.J. LOY, S. GOOLAUP, W.S. LEW School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore, Singapore

PJ-10 Electric Field-Induced Magnetic Anisotropy Change for Fe-Pt-Pd Alloys Satoru Kikushima(a), Takeshi Seki(a), Ken-ichi Uchida(a)(b), Eiji Saitoh(a)(c)(d)(e), Koki Takanashi(a) (a)Institute for Materials Research, Tohoku University, Sendai, Japan (b)PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan (c)Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan (d)WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan (e)Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan

A-35

Poster Session PK Magnetic Thin Films and Nanostructures

Wednesday Morning, Aug. 3rd, 2016 Room: Multifunction Room Chair: Hua-Shu Hsu/ National Pingtung University of Education PK-01 Spin Transport Properties of Amine-ended Single-Molecule Magnetic Junctions Kuan-Rong Chiang, Chia-Jung Lin, Yu-Hui Tang* Department of Physics, National Central University, Jhong-Li, Taoyuan, Taiwan PK-02 Study of the Formation and Switching Behaviour of Domain Wall in Permalloy Thin Film Rings Kao-Fan Lai, Li-Hao Chan, Deng-Shiang Shiu, and Lance Horng Department of Physics, National Changhua University of Education, Changhua, Taiwan PK-03 Aspect ratio dependence of ferromagnetic resonance in thin film ellipse arrays C. H. Li, H. T. Huang, and Z. Wei Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan PK-04 Thermoelectric property of ferromagnetic nanowire enhanced by substrate roughness S. H. Wang(a), H. T. Huang(b), and Z. Wei(b) (a)Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan

(b)Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

PK-05 Strain effects on magnetic Sm0.67Sr0.33MnO3 thin films S. L. Cheng, (a,b) T. H. Chuang,(a) and J. G. Lin (b)

(a)Department of Materials Science and Engineering, National Taiwan University (b)Center for Condensed Matter Sciences, National Taiwan University, Taipei,10617, Taiwan PK-06 Magnetic properties of NiFe permalloy films with Co-doping M.C. Chan(a)*, H.W. Chang(b) , D.W. Wei(a)

(a)Institute of Manufacturing Technology and Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (b)Department of Applied Physics, Tunghai University, Taichung 407, Taiwan PK-07 Exchange bias of MnPt/NiFe films with various ordering degree of L10-MnPt P.H. Pan(a)*, H.W. Change(a), C.R. Wang(a), Lance Horng(b)

(a)Department of Applied Physics, Tunghai University, Taichung, 407 Taiwan. (b)Department of Physics, National Changhua University of Education, Changhua 500, Taiwan. PK-08 Multiferroic properties of BiFeO3(110) films on CoPt(111) electrode layer on glass substrates at reduced temperatures C.C. Liu*, H.W. Chang

Department of Applied Physics, Tunghai University, Taichung 407, Taiwan PK-09 Magnetic Domain Wall Transfer in Discrete Magnetic Nanodot Chains M. Yang(a), H.-G. Piao(a,b), D.-H. Kim(b), L. Pan(a), and S.-C. Yu(b)* (a) College of Science, China Three Gorges University, Yichang 443002, P. R. China (b) Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea PK-10 Study of domain-wall motion by IrMn/CoFeB exchange bias in a magnetic wire Yun Hong(a), Deng-Shiang Shiu (a), Chi-Yang Lin (b), Kao-Fan Lai(a), Wu(a), Lance Horng(a) (a)Department of Physics, National Changhua University of Education, Changhua, Taiwan (b)Gaduate Institute of Photonics, Department of Physics, National Changhua University of Education, Changhua, Taiwan

A-36

Poster Session PL Soft/Hard Magnetic Materials

Wednesday Morning, Aug. 3rd, 2016 Room: Multifunction Room Chair: Cheng-Hsiang Chang/ NSRRC

PL-01 Study on the magnetic properties, thermal stability and corrosion resistance of the recycled sintered Nd-Fe-B magnets X. T. Li, W. Q. Liu*, M. Yue, X. W. Yin, D. T. Zhang College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, PR China PL-02 The mechanism of enhanced coercivity for the (Nd, Pr, Ce)-Fe-B magnet with dual main phases Rui Han, Hongsheng Chen, Liwei Song, Minggang Zhu, Shengzhi Dong and Wei Li Division of Functional Material, Central Iron & Steel Research Institute, Beijing 100081, P.R.China PL-03 Microstructure and Magnetic Properties of Nd Fe B Material Fabricated by Selective Laser Melting Kai Jyun Jhong * Wen His Lee National Cheng Kung University PL-04 Effect of the Gilbert damping constant on domain wall pinning in permanent magnets K. Yamada, and Y. Nakatani Graduate school of Informatics and Engineering, University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan

PL-05 Coercivity enhancement in hot-deformed Nd2Fe14B-type magnets by doping low melting point alloys Y. I. Lee, G. Y. Huang, C. W. Shih and W. C. Chang Department of Physics, National Chung Cheng University, Chia-Yi, 621 Taiwan, ROC PL-06 First Principle Calculation of Rare-Earth Dopant Partition and Magnetic Properties of RF3-doped Nd-Fe-B Die-Upset Magnet K. M. Kim(a), J. Y. Kim(a), H. W. Kwon(a), Imran Khan(a), J. S, Hong(a), J. G. Lee(b) and J. H. Yu(b), (a) Pukyong National University, Busan, Republic of Korea 48547 (b) Korea Institute of Materials Science, Changwon, Republic of Korea 51508 PL-07 Improvement of magnetic properties in microfabricated FePt/ Fe nano-composites upon post-annealing R. Kurosu, H. Iwama, A. Sugawara, M. Doi, T. Shima Faculty of Engineering, Tohoku Gakuin University, Tagajo, Japan PL-08 Effect of heat treatment on magnetic and electrical properties in Fe/Al2O3 core/shell nanocomposites S. Y. Tong, M. J. Tung, W. S. Ko and Y. P.Wang Material and Chemical Research Laboratories, Industrial Technology Research Institute, Taiwan

A-37

Plenary Talk 5 Ching-Ray Chang

13:30-14:15, Wednesday, Aug. 3rd, 2016 Room: 1st Lecture Hall Chair: Jauyn Grace Lin/ National Taiwan University

Spin transport within two dimensional layer materials

Ching-Ray Changa*, Han-Chun Wub, CY Chang, KC Chen, TW Huang

a) National Taiwan University, Taiwan b)Beijing Institute of Technology

Two dimension layer materials are substance of thickness with a few nanometers

or less, electrons in these materials are free to move in 2 dimension plane and restricted

to move along the perpendicular direction and governed by quantum mechanics. We

will concentrated on the interesting and exotic properties associated with spin and

charge transport within 2D layer materials. Taking into account of the intrinsic quantum

properties, we start from ab initio calculation of the band structures f 2D layer materials

and then use Laudauer-Kelydesh formalism to analyze their transport behavior. Several

different confined 2D materials experimental results will be presented, e.g., imperfect

graphene, AFM/FM bilayers and finite size effect of topological insulators. At last we

will also discussed the influence of spin-momentum locking on curved 2D layer system

which makes soft membrane can also be potential spintronics devices.

A-38

Session EA Magnetic Thin Films and Nanostructures II

Wednesday Afternoon, Aug. 3rd, 2016 Room: 3rd Lecture Hall Chair: Gung Chern/ National Chung Cheng University

Minn-Tsong Lin/ National Taiwan University 14:15-14:45 (Invited) EA-01 Scanning Tunneling Microscopy Study on Spintronic Emergent Materials Minn-Tsong Lin(a,b) (a)Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (b)Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan 14:45-15:15 (Invited) EA-02 The chiral symmetry in spin Hall effect G. Chern Physics Department and SPIN Center, National Chung Cheng University, Chiayi, Taiwan 15:15-15:45 (Invited) EA-03 Magnetism, gate tunable transport and magneto-transport in (Cr,Sb):Bi2Se3 epitaxial films on amorphous SiO2/Si Jung-Chun-Andrew Huang Physics Department, National Cheng Kung University, Taiwan 15:45-16:00 EA-04 Visualizing Spin-Dependent Molecule Symmetry at an Organic-Ferromagnetic Spinterface Yu-Hsun Chu(a), Chuang-Han Hsu(a), (b), Chun-I Lu(a), Hung-Hsiang Yang(a), Tsung-Han Yang(a), Chi-Hung Luo(a), Kai-Jheng Yang(a), Shih-Hao Hsu(a), Germar Hoffmann(a), (c), Chao-Cheng Kaun(b), (c), and Minn-Tsong Lin(a), (d), (e) * (a)Department of Physics, National Taiwan University, Taipei, Taiwan (b)Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (c)Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (d)Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan (e)Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

16:00-16:15 EA-05 A novel flexible magnetoelectric self-assembled BiFeO3-CoFe2O4 nanocomposite via van der Waal heteroepitaxy Tahta Amrillah(a), Yugandar Bitla(b), Kwangwoo Shin(c), Ying-Hui Hsieh(b), Liu-Heng Jui(b), Chih-Kuo Wang(b), Do Thi Hien(b), Ha Thai Duy(a), Yi-Ying Chin(4), Hong-Ji Lin(d), Kee Hoon Kim(c), Jenh-Yih Juang(a)*, and Ying-Hao Chu(a), (b)* (a)Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (b)Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (c)CeNSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea (d)National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan 16:15-16:30 EA-06 Magnetization Reversal of Nickel Three-Dimensional Antidot Arrays Le Yu(a),(d), Bingqing Li(a), Xuzhao Chai(a),(d), Han-chang Yang(a), Sina Moeendarbari(b), Yaowu Hao(b), Di Zhang(c), Gang Feng(c), Ping Han(d), Dustin A. Gilbert(e), Kai Liu(e), X. M. Cheng(a)

(a)Department of Physics, Bryn Mawr College, Bryn Mawr, PA 19010, USA (b)Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX 76010, USA (c)Department of Mechanical Engineering, Villanova University, Villanova, PA 19085, USA (d)School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China (e)Physics Department, University of California, Davis, CA 95616, USA 16:30-16:45 EA-07 Influences of magnetic anisotropy for Ni/(√3×√3)-Ag/Si(111) by silver capping layers Yu-Ting Chow, Bin-Han Jiang, and Jyh-Shen Tsay* Department of physics, National Taiwan Normal University, Taipei116, Taiwan

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16:45-17:00 EA-08 Structural and magnetic characterization of NiO/Co90Fe10 bilayers Yu-Chi Chang(a), Ko-Wei Lin(a), Johan van Lierop(b) (a)Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (b)Department of Physics and Astronomy, University of Manitoba, Winnipeg, R3T 2N2, Canada

17:00-17:15 EA-09 The contribution of thermal Hall effect in anomalous Nernst and spin Seebeck effects Yi-Jia Chen and Ssu-Yen Huang

Department of Physics, National Taiwan

University, Taipei, Taiwan

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Session EB Nanostructures with Potential Biomedical Applications

Wednesday Afternoon, Aug. 3rd, 2016 Room: 1st Lecture Hall Chair: Zung-Hang Wei/ National Tsing Hua University

Philip W. T. Pong/ The University of Hong Kong

14:15-14:45 (Invited) EB-01 Role of spin on future biomedical science: Logical manipulation of living cells for novel cells-on-chip Byungwha Lim, Sri Ramulu Torati, Xing Hao Hu, Sandhya Rani Goudu, CheolGi Kim* Department of Emerging Materials Science, DGIST, Daegu, 42988, Republic of Korea 14:45-15:15 (Invited) EB-02 Static and dynamic magnetic properties of intercellular magnetic nanoparticles for biomedical applications Yasushi Takemura Electrical and Computer Engineering, Yokohama National University, Japan 15:15-15:45 (Invited) EB-03 Magnetic Micro-shuttles: Bioengineering at the cellular level R. Sooryakumar Department of Physics, The Ohio State University

15:45-16:15 (Invited) EB-04 Development and application of spintronic sensors in smart and sustainable living Philip W. T. Pong, Y. Du, K. Zhu, X. Liu Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong 16:15-16:45 (Invited) EB-05 Preparation of magnetic iron oxide nanostructures and their applications Jun Ding Department of Materials Science & Engineering, National University of Singapore, Singapore 16:45-17:15 (Invited) EB-06 Spintronic linear motor for manipulation of magnetic beads Xiaoxi Liu Spin Device Technology Center, Shinshu University

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Session EC Functional Magnetic Materials and Characterization I

Wednesday Afternoon, Aug. 3rd, 2016 Room: 2nd Lecture Hall Chair: R. Nirmala/ Indian Institute of Technology Madras

Yu-Min Hu/ National University of Kaohsiung 14:15-14:45 (Invited) EC-01 The quest for Magnetocaloric materials: Rare earth intermetallics and Oxides R. Nirmala Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 INDIA 14:45-15:15 (Invited) EC-02 Electrical control of large magnetization reversal in a helimagnet Kee Hoon Kim CeNSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea 15:15-15:45 (Invited) EC-03 Conductance switching and tunneling characteristics of remotely controlled magnetostriction-based nanocontacts S. Narayana Jammalamadaka(a)*, Sebastian Kuntz(b), Oliver Berg(b), Wolfram Kittler(b), U. Mohanan Kannan(a), J. Arout Chelvane(c), and Christoph Sürgers(b)

(a)Magnetic Materials and Device Physics Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285, India (b)Karlsruhe Institute of Technology, Physikalisches Institut, Wolfgang Gaede Str. 1, Karlsruhe, 76131, Germany and (c)Defence Metallurgical Research Laboratory, Hyderabad 500058, India. 15:45-16:15(Invited) EC-04 Engineering ferromagnetic lines in graphene by local oxidation and hydrogenation using AFM lithography Bae Ho Park Department of Physics, Konkuk University, Seoul 143-701, Korea 16:15-16:45 (Invited) EC-05 Epitaxial Cobalt Ferrite Thin Films on Muscovite for Flexible Electronics Ying-Hao Chua,b,c

aDepartment of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan bInstitute of Physics, Academia Sinica, Taipei 11529, Taiwan cDepartment of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan 16:45-17:00 EC-06 Layered Structure of Magneto-Optical Kerr Rotation of [(GeTe)2(Sb2Te3)1]n Superlattices Do Bang(a,b,c), Hiroyuki Awano(a,b), Yuta Saito(c,d), Juni Tominaga(c,d) (a)Toyota Technological Institute, Nagoya, Japan (b)CREST, Japan Science and Technology Agency, Saitama, 332-0012, Japan (c)Institute of Materials Science, VAST, 18 Hoang Quoc Viet, Hanoi, Vietnam (d)Nanoelectronics Research Institute, National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Japan 17:00-17:15 EC-07 Heteroepitaxial CoFe2O4/Muscovite Bimorph with Large Magnetostriction for Flexible Electronics Chih-Kuo Wang(a), Heng-Jui Liu(a), Dong Su(b), Do Thi Hien(c), Ha Thai Duy(d), Kun-Hong Wu(e), Yi-Chun Chen(e), Jenh-Yih Juang(d), Qing He(f), Shien-Uang Jen(c),(g), and Ying-Hao Chu(a), (c), (d)* (a)Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan (b)Center for Functional Nanomaterials, Brookhaven National Laborator, NY 11973, United States (c)Institute of Physics, Academia Sinica, Taipei, Taiwan (d)Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (e)Department of Physics, National Cheng Kung University, Tainan, Taiwan (f)Department of Physics, Durham University, Durham DH1 3LE, United Kingdom (g)Institute of Optoelectronic Science, National Taiwan Ocean University, Keelung, Taiwan

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Poster Session PM Fundamental Properties & Computational Magnetism

Wednesday Afternoon, Aug. 3rd, 2016 Room: Multifunction Room Chair: Chi Kuen Lo/ National Taiwan Normal University

PM-01 The Magnetic Properties of Transition-metal Atom Adsorbed Two Dimensional GaAs Nanosheet Jia. Luo, Gang. Xiang,Tian Yu College of Physical Science and Technology, Sichuan University, Chengdu, 610064, China PM-02 Magnetic Properties of Weak Itinerant Electron Ferromagnet Au4V under high magnetic fields K. Koyama(a), A. Tanaka(a), S. Yoshinaga(a), Y. Mitsui(a), H. Sasaki(b), T. Kanomata(c) (a) Graduate School of Sci. & Eng., Kagoshima Univ., Kagoshima890-0065, Japan

(b)Faculty of Engineering, Tohoku-Gakuin University, Tagajyo 985-8537, Japan (c)Research Institute for Engineering and Technology, Tohoku Gakuin University, Tagajo 985-8537, Japan PM-03 Transmission Line Modelling of Strip-Mesh Screens Coated with Ferrite Sheet Hyun Ho Park(a), Jong Hwa Kwon(b), Sang Il Kwak(b), Seungyoung Ahn(c) (a)Department of Electronic Engineering, University of Suwon, Hwaseong, Korea (b) Electronics and Telecommunications Research Institute, Daejeon, Korea (c)The Cho Chun Shik Graduate School for Green Transportation, KAIST, Daejeon, Korea PM-04 Effect of sintering temperature on electrical transport mechanism and thermal properties of Pr2/3Sr1/3MnO3 Ramesh Chandra Bhatt(a), Ashok Rao(b)*, Mamatha D Daivajna(b),V. P. S. Awana(a), C. F. Lin(c), and Y. K. Kuo(c) (a)Quantum Phenomena and Applications Division, National Physical Laboratory (CSIR), New Delhi-110012, India (b)Department of Physics, Manipal Institute of Technology, Manipal University, Manipal-576104, India. (c)Department of Physics, National Dong-Hwa University, Hualien 974, Taiwan

PM-05 Frequency Dependence of Hysteresis Curves Based on Mean Field Model with Domain Structure Takashi Shirane, Yuuichi Takahashi National Institute of Technology, Sendai College, Sendai, Japan PM-06 Study the Stability of 360-degree Transverse domain-wall in a magnetic wire Yee-Mou Kao, Lung-Shiang Tsai, Deng-Shiang Shiu, Kuo-Chan Huang, Lance Horng

Department of Physics, National Changhua University of Education, Changhua, Taiwan PM-07 First-Principles Study of Electric Field Effects on Magnetic Anisotropy Energy in 2-Dimension VS2 Huei-ru Fuh(a), Ke-chuan Weng(b), Yeu-Chung Lin(a), and Ching-Ray, Chang(a)

(a)Department of Physics, National Taiwan University, No.1 Sec.4 Roosevelt Road Taipei 10617, Taiwan (b)Rearch Center for Applied Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan PM-08 Spin-Fluctuation Mechanism of Insulator-Metal Transition of Strongly Correlated Paramagnetic Compounds with pd-Hybridization A.A. Povzner, A.G. Volkov Ural Federal University, Ekaterinburg,620002. Russia

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Poster Session PN Spintronics Materials and Devices

Wednesday Afternoon, Aug. 3rd, 2016 Room: Multifunction Room Chair: Ssu-Yen Huang/ National Taiwan University

PN-01 First-principles calculation of electronic structure in NiMnSb/MgO and CoMnSb/MgO junctions M. Shirai(a), A. Onodera(a), M. Tsujikawa(a), Y. Miura(b) (a)Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan (b)Graduate School of Science and Engineering, Kyoto Institute of Technology, Kyoto 606-8585, Japan PN-03 Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junction Fa-Chieh Chu, Zhao-Wen Huang, Bao-Huei Huang, Yu-Hui Tang* Department of Physics, National Central University, Jhong-Li, Taoyuan, Taiwan PN-04 Optical observation of Spin wave excited by the magnetic vortex core oscillation Ming-Yi Kao, Liang-Juan Chang, Shang-Fan Lee Institute of Physics, Academia Sinica, Taipei, Taiwan PN-05 Effect of Ca substitution on the multiferroic properties of BiFeO3 films on glass substrates at reduced temperature S.Y. Lin(a), Y.C. Lo(a), K.T. Tu(a), C.R. Wang(a), C.S. Tu(b), H.W. Chang(a)* (a)Department of Applied Physics, Tunghai University, Taichung 407, Taiwan (b)Department of Physics, Fu Jen Catholic University, Taipei 242 Taiwan PN-06 Room temperature electrically tunable rectification magnetoresistance in Al/Ge Schottky devices Shi-shen Yan,* Huan-huan Li, Kun Zhang, Yu-feng Tian and Liang-mo Mei School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan

250100, P. R. China PN-07 Gate-controlled spin current diverter using 2D topological insulator and normal metal junction Chen Kuo-Chin, Chang Ching- Ray National Taiwan University, Taipei, Taiwan. PN-08 Micromagnetic Study of Spin-torque Nano-oscillators Dipolar-coupled with a Perpendicular Magnetized Layer Ching-Ming Lee*, Yuan-Yi Liao, Te-ho Wu*

Graduate School of Materials Science, National Yunlin University of Science and Technology, Douliou, 64002, Taiwan, R. O. C. PN-09 Spin-orbit torque in Pt/CoNiCo/Pt symmetric devices Meiyin Yang(a), Kaiming Cai(a), Hailang Ju(b), Kevin William Edmonds(c), Guang Yang(d), Shuai Liu(b), Baohe Li(b), Bao Zhang(a), Yu Sheng(a), ShouguoWang(d), Yang Ji(a) & Kaiyou Wang(a)

(a)SKLSM, Institute of Semiconductors, CAS, P. O. Box 912, Beijing 100083, People’s Republic of China (b)Department of Physics, School of Sciences, Beijing Technology and Business University, Beijing 100048, China (cSchool of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom (d)Department of Materials Physics and Chemistry, University of Science and Technology Beijing, 100083, China

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Poster Session PO Soft/Hard Magnetic Materials

Wednesday Afternoon, Aug. 3rd, 2016 Room: Multifunction Room Chair: Yuan-Chieh Tseng/ National Chiao Tung University

PO-01 Hyperfine structures and magnetic properties of MnxGa alloys A. Koeba, T. Shima and M. Doi Graduate school of engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo 985-0862, Japan PO-02 Synthesis of Mn-Bi Alloy using a Quenching Furnace under High Magnetic Fields Misaki Yamashita(a), Kenichi Abematsu(a), Khoki Takahashi(b), Yoshifuru Mitsui(a), Keiichi Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University, Kagoshima,890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan PO-03 Comparison of hydrogen decrepitation behaviors between (La, Ce)-Fe-B and Nd-Fe-B strips Jiaying Jin, Yujing Zhang, Guohua Bai, Tianyu Ma, and Mi Yan School of Materials Science and Engineering, State Key Laboratory of Silicon materials, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Zhejiang University, Hangzhou 310027, China PO-04 Structure and magnetic properties of FeCoAlBN soft magnetic films prepared by pulsed laser deposition Guohua Bai, Chen Wu and Mi Yan School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China PO-05 Novel fabrication method of soft magnetic thin ribbons K. Eguchi, K. Azuma, T. Akiyoshi, T.Yanai, M. Nakano, H. Fukunaga Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

PO-06 Rare earth thick film magnets deposited on glass substrates for MEMS application K. Hirotaki(a), A. Yamashita(a), M. Nakano, (a) T. Yanai(a), R. Fujiwara(b), T. Shinshi(b), and H. Fukunaga(a) (a)Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan (b)Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama 226-8503, Japan PO-07 DC/pulse plating of Fe-Ni-Co films K. Eguchi, K. Azuma, T. Akiyoshi, T. Yanai, M. Nakano, H. Fukunaga Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan PO-08 Local geometric and electronic structures, and magnetic properties of Mn-doped SrTiO3 T. L. Phan(a), N. Tran(a), B. W. Lee(a), T. A. Ho(b), T. D. Thanh(c), S. C. Yu(c) (a)Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791, South Korea (b)Department of Materials Science and Engineering, Korea University, Seoul 136-713, South Korea (c)Institute of Materials Science, Vietnam Academy of Science and Technology, Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam PO-09 Magnetic-field driven second-order phase transition to the first order in Pr-doped La0.7Ca0.3MnO3 T. L. Phan(a), P. T. Tho(a), C. L. Liu(a), T. A. Ho(b), S. H. Lim(b) (a)Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791, Korea (b)Department of Materials Science and Engineering, Korea University, Seoul 136-713, South Korea

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4th August, Thursday

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Plenary Talk 6 Kang L. Wang

08:45-09:30, Thursday, Aug. 4th, 2016 Room: 1st Lecture Hall Chair: Te-Ho Wu/ National Yunlin University of Science and Technology

Spin-Orbitronics for Energy Efficient Systems Kang L. Wang

Electrical Engineering Department, University of California, Los Angeles, CA 90095, USA

E: wang@ee.ucla.edu;

Energy dissipation has become the major challenge for the current electronics. This is due to the leakage current and the voltage scaling limit of nanoscale structures and devices. With nonvolatile magnetic memory and alike, the leakage current may be minimized and the voltage scaling may be further advanced due to the collective behavior. Meanwhile, spin-orbit coupling (SOC), a relativistic effect which describes the coupling between the orbital and spin degrees of freedom, has become the spotlight in the field dubbed as spin-orbitronics. In continuing effort to resolve these challenges, I will first discuss the engineering of interface SOC to illustrate the efficient control of magnetic memory, in addition to the present approach of channel and tunneling barrier engineering. The engineering of SOC results in the electric field control of magnetic moment or magneto-electric (ME) effect, which shows in orders of magnitude improvement in energy dissipation compared with the current spin transfer torque memory (STTRAM). Likewise, a large SOC is also shown to give rise to a large spin-orbit torque or SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for highly efficent spin-orbit torque (SOT). I will show magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. This large SOT deriving from the spin-momentum locked surface states of TI may be used to improve the energy efficiency for applications. In addition, the recent progress in Skyrmions, a topologically protected nanoscale magnetic textured structures, will be discussed in reference to the creation and manipulation of their dynamics; low energy manipulation of the skyrmions has been demonstrated. Finally, the integration of these types of spintronics devices with CMOS for intelligent systems will be discussed.

*The work was in part supported by ERFC-SHINES, ARO, TANMS, and FAME

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Session FA Fundamental Properties & Computational Magnetism II

Thursday Morning, Aug. 4th, 2016 Room: 3rd Lecture Hall Chair: Chiung- Wu Su/ National Chiayi University

Soon Cheol Hong/ Ulsan University 09:30-10:00 (Invited) FA-01 Quantum anomalous Hall phases in layered magnetic oxides predicted by first-principles density functional calculations Guang-Yu Guo

Department of Physics, National Taiwan University, Taipei 10617, Taiwan 10:00-10:30 (Invited) FA-02 On searching for 2-dimensional (2D) magnetic semiconductors based on 2D Transition-Metal Dichalcogenides (TMD) Huei-Ru Fuh (a), Kai-Wei Chang (b), Horng-Tay Jeng (c) (a) Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan (b) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (c) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan 10:30-11:00 (Invited) FA-03 Roles of nonmagnetic elements in magnetic devices: first-principles studies Soon Cheol Hong, P. Taivansaikhan, Soyoung Jekal, S. H. Rhim 1Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 44610, Republic of Korea 11:00-11:15 FA-04 Electric-field Control of Skyrmion Motion H. T. Fook, W. L. Gan, W. S. Lew School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore

11:15-11:30 FA-05 Enhanced anisotropic FMR linewidths under rotating magnetic fields in Fe-Si (001) single-crystal-film planes Shinji Isogami(a), Tetsuroh Kawai(b) and Masaaki Futamoto(b) (a)Department of Physics, Fukushima National College of Technology, Iwaki-City, Fukushima 970-8034, Japan (b)Faculty of Science and Engineering, Chuo University, Bunkyo-Ku, Tokyo 112-8551, Japan 11:30-11:45 FA-06 In-magnetic-field Annealing for Mn-based alloys Y. Mitsui(a), R. Kobayashi(a), R. Y. Umetsu(b), K. Takahashi(b), M. Mizuguchi(b), K. Koyama(a) (a)Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-857, Japan 11:45-12:00 FA-07 Three terminal skyrmion device for memory applications W. L. Gan, H. T. Fook, W. S. Lew School of Physical & Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore

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Session FB Spintronic Materials & Devices III

Thursday Morning, Aug. 4th, 2016 Room: 1st Lecture Hall Chair: Ying-Hao Chu/ National Chiao Tung University

Hyunsoo Yang/ University of Singapore

09:30-10:00 (Invited) FB-01 Three-terminal Spintronics Devices for CMOS Integration Hideo Ohnoa,b,c,d aCenter for Spintronics Integrated Systems, Tohoku University bCenter for Innovative Integrated Systems, Tohoku University cLaboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University dWPI-AdvancedInstitute for Materials Research, Tohoku University 10:00-10:30 (Invited) FB-02 Relativistic motion of antiferromagnetic domain wallsdriven by spin-orbit torques Takayuki Shiinoa, Se-Hyeok Ohb, Byong-Guk Parka, and Kyung-Jin Leeb,c aDepartment of Materials Science and Engineering, KAIST, Daejeon 305-701, Korea bDepartment of Material Science and Engineering, Korea University, Seoul 136-701, Korea cKU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-713, Korea 10:30-11:00 (Invited) FB-03 Strain engineered magnetic tunnel junctions and spin-orbit torque switching Xuepeng Qiu, Li Ming Loong, Kulothungasagaran Narayanapillai, Yi Wang, Jiawei Yu, Jungbum Yoon, and Hyunsoo Yang Department of Electrical and Computer Engineering, National University of Singapore, Singapore

11:00-11:15 FB-04 Magnetic Chirality in the Enantiopure CsCuCl3 Crystals K. Ohishi(a), Y. Kousaka(b), T. Koyama(b), K. Kakurai(c), V. Hutanu(d), Th. Brueckel(e), Y. Miyamoto(b), A .Sera(b), E. Proskurina(f), T. Ogura(f), A. Koda(g), K. M. Kojima(g), H. Luetkens(h), A. Amato(h), J. Suzuki(a), K. Inoue(b), and J. Akimitsu(b) (a)Neutron Science Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan (b)Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan (c)Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan (d)RWTH Aachen University, Institut für Kristallographie, D-52056 Aachen, Germany (e)Juelich Centre for Neutron Science JCNS-FRM II, Forschungszentrum Juelich GmbH, Outstation at FRM II, Lichtenbergstr. 1, D-85747 Garching, Germany (f)Department of Physics and Mathematics, Aoyama-Gakuin University, Sagamihara, Kanagawa 252-5258, Japan (g) Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan (h) Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland

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Session FC Magnetic Thin Films and Nanostructures III

Thursday Morning, Aug. 4th, 2016 Room: 2nd Lecture Hall Chair: Bo-Yao Wang/ National Changhua University of Education

Jung-Woo Yoo/ UNIST

09:30-10:00 (Invited) FC-01 Spintronics with carbon-based materials Jung-Woo Yoo School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Republic of Korea 10:00-10:30 (Invited) FC-02 Giant negative magnetoresistance in Mn-substituted ZnO X. L. Wanga, Q. Shaob, R. Lortzb, J. N. Wangb, A. Ruotolo1 aDepartment of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong, SAR China bDepartment of Physics, Hong Kong University of Science and Technology, Kowloon, Hong Kong, SAR China 10:30-11:00 (Invited) FC-03 Spectromicrosopic studies of defects in association with ferromagnetism of ceria based nanoparticles Shih-Yun Chen National Taiwan University of Science and Technology, Taiwan 11:00-11:30 (Invited) FC-04 Magnetic micro-/nano- structures for bio-applications H. T. Huang, C. Y. Huang, and Z. H. Wei* Department of Power Mechanical Engineering, National Tsing Hua University, Taiwan

11:30-11:45 FC-05 Enhanced Magnetic Ordering of F4-TCNQ on Ni Surface Ming-Wei Lin(a), Po-Hong Chen(a),(b), Yu-Ling Lai(a), Der-Hsin Wei(a), and Yao-Jane Hsu(a) (a)National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu, Taiwan (b)Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan 11:45-12:00 FC-06 Surface morphology, magnetism and chemical state of Fe coverage on MoS2 substrate Hung-Chang Hsu(a), Chii-Bin Wu(b), Kai-Lin Hsu(a), Po-Chun Chang(a), Tsu-Yi Fu(a), Venkata Ramana Mudinepalli(a), Wen-Chin Lin(a) (a)Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (b)Department of Physics, Chung Yuan Christian University, Chungli 32023, Taiwan

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Poster Session PP Spintronics Materials and Devices

Thursday Morning, Aug. 4th, 2016 Room: Multifunction Room Chair: Chin-Chung Yu/ National University of Kaohsiung

PP-01 Direct Probe of the Spin-momentum locking Effect of NiFe/BiSe Topological Insulator Device Yu-Jung Chen (a) , Pei-Yu Chuang(a) , Shu-Jui Chang(a), Cheong-We Chong (a) , Jung-Chun-Andrew Huang (b) , and Yuan-Chieh Tseng(a)* (a)Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (b)Dept. Materials Science & Engineering, National Chiao Tung University, Hsinchu, Taiwan. PP-02 Inverse Spin Hall effect in cobalt thin films Yi-Chien Weng, (a),(b) C-T. Liang(b), and J. G. Lin(a),* (a)Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan

(b)Graduate Institute of Applied Physics, National Taiwan University, Taipei 10617, Taiwan PP-03 Tuning the Schottky barrier of two-dimensional lateral heterostructure by strain engineering Hwihyeon Hwang, Jaekwang Lee* Department of Physics, Pusan National University, Busan, 46241, Republic of Korea PP-04 Effect on Defect in Mn-doped Ferromagnetic AlGaP2 Semiconductor Byung-Sub Kang(a), Kie-Moon Song(a), Kyeong-Sup Kim(b), Seong-Cho Yu(b), and Haeng-Ki Lee(c)

(a)Nanotechnology Research Centre, Dept. of Nano science and Mechanical engineering, Konkuk University, Chungju, 27478, South Korea (b)Dept. of Physics, Chungbuk National University, Cheongju, 28644, South Korea (c)Dept. of Radiotechnology, Suseong College, Daegu, 42078, South Korea

PP-05 Study of domain-wall motion by IrMn/CoFeB exchange bias in a magnetic wire Deng-Shiang Shiu (a), Chi-Yang Lin (b) (a)Department of Physics, University of A, A-City, Taichung, Taiwan (b)School of Engineering, University of B, B-Town, 222, Republic of B PP-06 The Spin Electron Moves on Line Defect in Honeycomb Structure Tsung-Wei Huang(a)* and Ching-Ray Chang(a),

(b)† (a)Department of Physics, National Taiwan University, Taipei 10617, Taiwan (b)Graduate Institute of Applied Physics, National Taiwan University, Taipei s10617, Taiwan PP-07 Variations of the Kerr Signals of the NiFe/ZnO Bilayers Under Voltage Modulations Zheng-Wei Lin, Chin-Chung Yu, Hsin-Hua Ko Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan PP-08 Fabrication and Characterization of Fully-Epitaxial Superconductor/Half-Metallic Heulser Alloy Films I. Shigeta(a), T. Kubota(b), K. Makise(c), S. Kimura(b), S. Awaji(b), B. Shinozaki(d), K. Koyama(a), K. Takanashi(b), M. Hiroi(a) (a)Grad. School of Sci. & Eng., Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan (c)National Institute of Informa. & Communi. Tech., Hyogo 651-2492, Japan (d)Department of Physics, Kyushu University, Fukuoka 812-8581, Japan

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PP-09 Strain induced modulations of the Kerr signal and coercivity of the NiFe films Chin-Chung Yu, Hsin-Hua Ko, Zheng-Wei Lin Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan PP-10 Spin texture changes in different surfaces of topological insulator Bi2Se3 Ming-Chien Hsu(a), Heui-Ru Fuh(b), Ke-Chuan Weng(c), Yeu-Chung Lin(b) and Ching-Ray Chang (b) (a)Department of Electrical and Computer Engineering, National University of Singapore, Singapore (b)Department of Physics, National Taiwan University, Taiwan (c)Research Center for Applied Sciences, Academia Sinica, Taiwan

PP-11 Perpendicular magnetic anisotropy of Non-magnetic Materials/ Ferromagnetic Materials/MgO trilayer In Ho Cha(a), Yong Jin Kim(a), Gyu Won Kim(a), Young Keun Kim(a) (a)Department of Materials Science and Engineering, Korea University, Seoul 02841 Korea

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Poster Session PQ Magnetic Materials Applications(sensors, motors, RF devices)

Thursday Morning, Aug. 4th, 2016 Room: Multifunction Room Chair: Jen-Tzong Jeng/ National Kaohsiung University of Applied Sciences

PQ-01 Influence of Magnetic Structures on the High-frequency Characteristics of Bilayer Composite Structures W. C. Tang(a), H. T. Huang(b), and Z. Wei(b) (a)Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan

(b)Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

PQ-02 Durability Improvement of High-Resolution MFM Tips Masaaki Futamoto, Kei Kato, Yuma Tomita, Mitsuru Ohtake Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan PQ-03 Sensitivity of a Fluxgate Sensor Using Magnetic-Domain-Controlled Amorphous Core H. Miyata(a), R. Yamamoto(b), Y. Morimoto(b), M. Takezawa(b) (a) MTI Co., Ltd., Kitakyushu, Japan (b) Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu, Japan PQ-04 Fabrication and Dispersion of Fe3O4 Nanopowder using Co-Precipitation Method for Magnetic Fluid Preparation. Jung-Kab Park, Seung-Bin Baeg, Yung-Il Song, Su-Jeong Suh School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea PQ-05 Magnetically Barcoded Microcarriers Detection with TMR sensors Pratap Kollu, Adrian Ionescu,

David M. Love, C. Cimorra, Justin Llandro and C.H.W. Barnes

Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK

PQ-06 Design Optimization of an SPM Motor With Minimized Usage of Rare-Earth Magnets C. T. Liu(a), C. C. Hwang(b), C. J. Hong(c) (a) Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung 804, Taiwan (b) Department of Electrical Engineering, Feng Chia University, Taichung 407, Taiwan (c) Ph.D. Program in Electrical and Communications Engineering, Feng Chia University, Taichung 407, Taiwan PQ-07 Design of a Coaxially Magnetic-geared Linear Actuator for Electric Power Steering System Applications Cheng-Tsung Liu(a), Chang-Chou Hwang(b), Yu-Wen Chiu(a) (a)Dept. of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (b)Dept. of Electrical Engineering, Feng Chia University, Taichung, Taiwan PQ-08 Fundamental Analysis of a PMSM with High Flux Density Using FEM K. Miyahara, R. Ishikawa and T. Yoshida Department of Electrical Engineering, Kyushu University, Japan PQ-09 Completely Accessible Self-controlled Electronics Wheelchairs Motor Driver to Stabilization of Acceleration of Gravity Shun-Yuan Wang, Savrina Tung Department of Electrical Engineering, National Taipei University of Technology, Taiwan

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PQ-10 Design and Reduction of Thrust Ripple in Transverse Flux Permanent Magnet Linear Machine Mei Zhao(a)* (b) (c), Fujun Han(a), Yunliang Zhang(c), Huixia Liu(a), Jibin Zou(b) (a)Department of Information and Electrical Engineering, Ludong University, Yantai, 264025, CHINA (b)Department of Electrical Engineering, Harbin Institute of Technology, Harbin, 150001, CHINA (c)Weihai Guangtai Airport Equipment CO., Limited, Weihai,264200, CHINA PQ-11 Design and Analysis of Magnetic Transmission for Converting Between Rotary and Rectilinear Motion Xinghe Fu*, Biao Wang, Kai Liu, Mingyao Lin School of Electrical Engineering, Southeast University, Nanjing, China PQ-12 Magnetic Field Analysis of a Novel Transverse Flux Switched-flux Permanent Magnet Linear Motor Mei Zhao(a)* (b) (c), Yunliang Zhang(c), Fujun Han(a), Huixia Liu(a), Jibin Zou(b) (a)Department of Information and Electrical Engineering, Ludong University, Yantai, 264025, CHINA (b) Department of Electrical Engineering, Harbin Institute of Technology, Harbin, 150001, CHINA (c)Weihai Guangtai Airport Equipment CO., Limited, Weihai,264200, CHINA PQ-13 Miniaturization of Implantable Micro-robot Propulsion using Wireless Power Transfer System D. Kim(a), K. Hwang(a), J. Park(a), H.H Park(b), and S. Ahn(a) (a)The CCS GSGT Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea (b)Department of Electronic Engineering, The University of Suwon, Hwaseong, Republic of Korea PQ-14 Application of SynRM Driving CVT System Using Blend Recurrent Gegenbauer OPNNAPSO Control Chih-Hong Lin Department of Electrical Engineering, National United University, Miaoli, Taiwan

PQ-15 Integrated Design of Magnetic Gear and Electric Motor for Electric Vehicles Mi-Ching Tsai(a)*, Yi-Chang Wu(b), Chin-Tsung Chan(b), Pei-Yi Cai(c), Po-Wei Huang(c), and Ming-Hsiao Tsai(c) (a)Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan (b)Department of Mechanical Engineering, National Yunlin University of Science & Technology, Yunlin, Taiwan (c)Electrical Motors Technology Research Center, National Cheng Kung University, Tainan, Taiwan PQ-16 Magnetic and transport properties of epitaxial CoxFe3-xO4 thin films on MgO (100) Quang Van Nguyen(a), Christian Meny(b), S. H. Rhim(a), Yooleemi Shin(b), Duong Anh Tuan(a), and Sunglae Cho(a)

(a)Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of Korea (b)Institute of Physics and Chemistry for Materials of Strasbourg, UMR 7504 UDS-CNRS, Strasbourg 67034, France PQ-17 Monitoring and Damping UMP Due Eccentricity Fault in Induction Machines: A Review Ahmad Salah(a), David Dorrell(b) and Youguang Guo(a) (a)School of Electrical, Mechanical and Mechatronic Systems University of Technology Sydney, Broadway, Sydney, NSW 2007, Australia (b)Discipline of Electrical, Electronic and Computer Engineering, Faculty of Engineering University of KwaZulu-Natal, Howard College, Durban, 4041, South Africa PQ-18 Design of a Single-Phase DC-Excited Flux Switching Machine for Home Appliance with Improved Starting Toque Zih-Cing You*, Chung-Wen Yu, and Sheng-Ming Yang Department of Electrical Engineering, National Taipei University of Technology, Taiwan

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PQ-19 Design of a Pseudo Direct Drive for Wind Power Applications C. G. C. Neves(a)*, A. F. Flores Filho(b), D. G. Dorrell(c)

(a)Curso de Eng. de Energia, Universidade Federal do Pampa, Brazil (b)DELET, Universidade Federal do Rio Grande do Sul, Brazil (c)Discipine of Electrical, Electronic and Computer Engineering, Faculty of Engineering University of KwaZulu-Natal, Howard College Campus, Durban, 4041, South Africa PQ-20 Design of a Pseudo Direct Drive for Wind Power Applications C. G. C. Neves(a)*, A. F. Flores Filho(b), D. G. Dorrell(c)

(a)Curso de Eng. de Energia, Universidade Federal do Pampa, Brazil (b)DELET, Universidade Federal do Rio Grande do Sul, Brazil (c)Discipine of Electrical, Electronic and Computer Engineering, Faculty of Engineering University of KwaZulu-Natal, Howard College Campus, Durban, 4041, South Africa

PQ-21 Improved Non-Linear Torque Sharing Function Applied to Torque Ripple Reduction of Switched Reluctance Motor Min-Fu Hsieh(a)*, Chung Chan Hsu(a), Hao-Yu Ting(b), Po-Ying Li(b), Le-Ren Chang-Chien(b) and Yu-Hsien Li(a)1

(a) Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University, Taiwan (b) Department of Electrical Engineering, National Cheng Kung University, Taiwan PQ-22 AC Copper Losses Analysis of the Ironless BLDCM used in a Flywheel Energy Storage System Kai Liu, XinHe Fu, MingYao Lin

School of Electrical Engineering, Southeast University, Nanjin, China

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Poster Session PR Soft/Hard Magnetic Materials

Thursday Morning, Aug. 4th, 2016 Room: Multifunction Room Chair: Huang-Wei Chang /Tunghai University

PR-01 Anisotropic Sm-Co/α-Fe thick film-magnets prepared by two-step annealing Yuya Furukawa*, Xu Han, Hiroaki Koga, Takeshi Yanai, Masaki Nakano, Hirotoshi Fukunaga School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan PR-02 Effect of phase structure on remanence thermal stability of Alnico8 alloys J.T.Zhao, Y.L.Sun, Z.Liu, D.Lee,L.Liu, X.C.Feng and A.R.Yan Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, ChineseAcademy of Sciences,Ningbo, 315201, China PR-03 Effect of bath temperature on structural and magnetic properties of Fe22Ni78 films electroplated in a deep-eutectic-solvent-based bath K. Azuma, T. Akiyoshi, T. Yanai, M. Nakano, H. Fukunaga Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan PR-04 High-speed Fe plating using DES-based plating baths T. Akiyoshi, K. Azuma, T. Yanai, K. Eguchi, M. Nakano, H. Fukunaga Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan PR-05 Fe-Pt thick films prepared by a pulse plating method T. Masaki, T. Yanai, K. Furutani, M. Nakano, H. Fukunaga Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

PR-06 Effect of an additive in DES-based baths on magnetic properties of electroplated magnetic films T. Akiyoshi, K. Azuma, T. Yanai, K. Eguchi, M. Nakano, H. Fukunaga Nagasaki University, Nagasaki-City, Nagasaki 852-8521, Japan PR-07 Investigation of magnetic properties of electroplated permalloy for flux-guide application Bipul Das(a), Meng-Syun Jhou(a), Cheng-Yun Lee(a), C. H. Lee(b), J. T. Jeng(c), Van Su Luong(c), J. H. Hsu(d), C. R. Chang(d), Lance Horng(a) and Jong-Ching Wu(a) (a)National Changhua University of Education, Changhua 500, Taiwan (b)National Tsing Hua University, Kuang-Fu Road, Hsinchu 30013, Taiwan (c)National Kaohsiung University of Applied Sciences, Chien Kung Road, Kaohsiung 807, Taiwan (d)National Taiwan University, Roosevelt Road, Taipei 10617, Taiwan PR-08 Production of nanocrystalline Fe-Si-B-P-Nb-Cu alloys with excellent soft magnetic properties for commercial applications Zongzhen Li, Shaoxiong Zhoua, Guangqiang Zhang, Bangshao Dong, Hui Gao China Iron & Steel Research Institute Group, Advanced Technology & Materials Co., Ltd., Beijing 100081, China

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Plenary Talk 7 Steve Hwang

13:30-14:15, Thursday, Aug. 4th, 2016 Room: 1st Lecture Hall Chair: Min-Fu Hsieh/ National Cheng Kung University

Storage Marches On

Steve Hwang

Vice President, Media Research and Development, Seagate Technology e-mail: steve.hwang@seagate.com

In recent years, the proliferation of social media, smartphones, video storing and

sharing, archiving, and surveillance has resulted in data being generated at an exponential rate & volume. The increased focus on the value of big data further contributed to ever increasing demand for storage, especially in the cloud.

Figure 1 To satisfy this demand, it is not cost effective to simply build more factories. Instead,

new technologies like Heat Assisted Magnetic Recording (HAMR) & Heated Dot Magnetic Recording (HDMR) are necessary to take the industry to the next areal density S curve.

I will discuss the various technology

developments, and how Seagate addresses the different markets with its broad portfolio of products.

[1] Seagate Strategic Marketing & Research

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Session GA Soft/Hard Magnetic Materials II /Functional Material and Application

Thursday Afternoon, Aug. 4th, 2016 Room: 3rd Lecture Hall Chair: De-Ren Li/ Advanced Technology and Materials Co., Ltd.

Huang-Wei Chang/ Tunghai University 14:15-14:45 (Invited) GA-01 Microstructure and magnetism of a Nd-Fe-B sintered magnet investigated using synchrotron X-rays Tetsuya Nakamura aJapan Synchrotron Radiation Research Institute (JASRI) / SPring8 b ESICMM / NIMS 14:45-15:15(AUMS Young research award) GA-02 Compact STXM: Development and Application for Magnetic Materials Y. Takeichi Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801 Japan 15:15-15:45 (Invited) GA-03 Realization of Ground-State Artificial Skyrmion Lattices at Room Temperature Dustin A. Gilbert(a),(b), Brian B. Maranville(b), Andrew L. Balk(c),(d), Brian J. Kirby(b), Peter Fischer(e),(f), Daniel T. Pierce(c), John Unguris(c), Julie A. Borchers(b) & Kai Liu(a) (a)Department of Physics, University of California, Davis, California 95616 (b)NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (c)Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (d)Maryland Nanocenter, University of Maryland, College Park, Maryland 20742 (e)Center for X-Ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (f)Department of Physics, University of California, Santa Cruz, California 94056

15:45-16:00 GA-04 Spin torque in topological insulator thin films Z.B. Siu(a), M.B.A. Jalil(a) and S.G. Tan(b) (a) National University of Singapore, Singapore (b) Data Storage Institute, Singapore 16:00-16:15 GA-05 Long-range transfer of electron-phonon coupling in BFO-based heterostructures Ping-Fan Chen,(a) Yen-Lin Huang,(b) Jan-Chi Yang,(b) Heng-Jui Liu,(b) Jiunn-Yuan Lin,(c) Ying-Hao Chu.(a),(b) (a)Institute of Physics, Academia Sinica, Taipei 11529 (b)Department Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010 (c)Institute of Physics, National Chiao Tung University, Hsinchu 30010 16:15-16:30 GA-06 High switching efficiency in ferrimagnet spin-orbit torque devices Rahul Mishra, Xuepeng Qiu and Hyunsoo Yang Department of Electrical and Computer Engineering, National University of Singapore, Singapore

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Session GB Spintronic Materials & Devices IV

Thursday Afternoon, Aug. 4th, 2016 Room: 1st Lecture Hall Chair: Cen-Shawn Wu/ National Changhua University of Education

Chi-Feng Pai/National Taiwan University

14:15-14:45 (Invited) GB-01 Effect of Interface-Assisted Molecular Ordering on the Operation of Organic Spintronic Devices Tae Hee Kim Dept. of Physics, Ewha Womans University, Seodaemun-gu, Seoul03760, Rep. of Korea 14:45-15:15 (Invited) GB-02 Vortex-state nanoparticles for bio-imaging and magnetic hyperthermia Sang-Koog Kim National Creative Research Initiative Center for Spin Dynamics and Spin-Wave Devices, Nanospinics Laboratory, Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, South Korea 15:15-15:45 (Invited) GB-03 Spin polarized tunneling study on spin Hall effect metals and topological insulators Luqiao Liu Electrical Engineering & computer Science, MIT 15:45-16:15 (AUMS Young research award) GB-04 Spin-Orbit Torque Control of Magnetic Insulator with Perpendicular Magnetic Anisotropy Chi-Feng Pai(a,b), Andy Quindeau(b), Astera S. Tang(b), Maxwell Mann(b), Lucas Caretta(b), Mehmet C. Onbasli(b), Caroline A. Ross(b), and Geoffrey S. D. Beach(b) (a)Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (b)Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America

16:15-16:45 (Invited) GB-05 Towards Novel Spintronic Materials Discovery by X-ray Yuan-Chieh Tseng Dept. of Materials Science& Engineering, National Chiao Tung University 1001 Ta Hsueh Road, Hsin-Chu, Taiwan 30010 16:45-17:00 GB-06 Enhanced current- perpendicular -to-plane giant magnetoresistance effect in half-metallic NiMnSb Heusler alloy based nano-junctions with multiple Ag spacers Zhenchao Wen, Takahide Kubota, Tatsuya Yamamoto, and Koki Takanashi Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan 17:00-17:15 GB-07 Noncollinear magnetization between Surface and Bulk Y3Fe5O12 Po-HsunWu and Ssu-Yen Huang Department of Physics, National Taiwan University, Taipei, Taiwan

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Session GC Functional Magnetic Materials and Characterization II

Thursday Afternoon, Aug. 4th, 2016 Room: 2nd Lecture Hall Chair: Chien-Cheng Kuo/ National Sun Yat-sen University

Jung-Il Hong/ DGIST

14:15-14:45 (Invited) GC-01 Ferromagnetism at the Surface of Antiferromagnet Induced by the Exchange Coupling in the Nanogranular Layer Jung-Il Hong, Min-Seung Jung Department of Emerging Materials Science and DGIST Center for Emerging Materials, DGIST, Daegu 42988, Korea 14:45-15:15 (Invited) GC-02 All-optical manipulation of magnetization and ultrafast non-local spin dynamics Arata Tsukamoto College of Science and Technology, Nihon University, Funabashi, Chiba, Japan 15:15-15:45 (Invited) GC-03 Synchrotron X-ray Scanning Tunneling Microscopy: A Novel Approach for the Nanoscale Characterization of Functional Magnetic Materials with Chemical Contrast Volker Rose X-ray Science Division & Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4800, U.S.A. Physics & Astronomy Department Ohio University, Athens, OH 45701, USA 15:45-16:15 (Invited) GC-04 When ferromagnetic metals meet organics -- A synchrotron investigation of hybrid organic spin-valve D. H. Wei, K. T. Lu, C. I. Lu, T. H. Chuang, Y. J. Hsu National Synchrotron Radiation Research Center, Hsinchu, Taiwan

16:15-16:30 GC-05 Investigation of multiferroic Bi(Pb)FeO3/SrRuO3/SrTiO3 heterostructure by Rutherford backscattering Murtaza Bohra(a), K. Negi(a), Varun Karthik Y.S.(a), H. Chou(b), X. Wang(c) and W-K Chu(c) (a)Mahindra Ecole Centrale, Hyderabad, India (b)National Sun Yat-Sen University, Kaohsiung, Taiwan, (c)Texas Center of Superconductivity, University of Houston, USA. 16:30-16:45 GC-06 Large magnetocaloric effect in Ni-Mn-Ga-Cu ferromagnetic shape memory alloys Dewei Zhao, Jian Liu Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China

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Poster Session PS Magnetic Thin Films and Nanostructures

Thursday Afternoon, Aug. 4th, 2016 Room: Multifunction Room Chair: Hua-Shu Hsu/ National Pingtung University of Education PS-01 Termination Effect of LSMO on Interfacial Electronic and Magnetic Properties in Alq3-based Organic Spintronics Tu-Ngoc Lam(a), Ming-Wei Lin(b), Yu-Ling Lai(b), Hong-Ji Lin(b), Ying-Hao Chu(c), Yao-Jane Hsu*(b),(d) (a) Institute of Nanotechnology, National Chiao Tung University, Hsinchu, Taiwan (b) National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan (c)Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan (d) Department of Photonics, National Cheng Kung University, Tainan, 70101, Taiwan PS-02 Voltage induced reversible and irreversible change of magnetic coercivity in Co/ZnO heterostructure Chuan-Che Hsu, Po-Chun Chang, Venkata Ramana Mudinepalli, Tsung-Chun Hsieh, Fang-Yuh Lo, and Wen-Chin Lin Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan PS-03 Modulating magnetic anisotropy by stress/strain in flexible magnetic thin films Baomin Wang(a),(b), Yiwei Liu(a), (b), Qingfeng Zhan(a), (b), and Run-Wei Li(a), (b) (a)Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China (b)Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China

PS-04 Annealing-induced alloy formation in Pd/Fe bilayers on Si (1 1 1) for hydrogen sensing Venkata Ramana Mudinepalli(a),*, Cheng-Jui Tsai(a), Ying-Chin Chuang(a), Po-Chun Chang(a), N. Plusnin(b), Wen-Chin Lin(a) (a)Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan. (b)Institute of Automation and Control Processes, 5 Radio Str., Vladivostok, Russia. PS-05 Effects of Fe content on the magnetic properties and microstructure of Pr-Fe-B thin films Ching-Fong Shea, Yu-Shen Chen, and An-Cheng Sun Department of Chemical Engineering and Material Science, Yuan-Ze University, Chung-Li, Taoyuan, Taiwan PS-06 Voltage-controlled in the magnetic exchange coupling of Fe /ZnO/Zn1-xFexO heterostructures Po-Chun Chang, Fang-Yu Lo, Wen-Chin Lin* Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan PS-07 Magnetic properties and related structures for Co-rubrene composite films Yong-Jhih Hou, Cheng-Hsun-Tony Chang, Chun-Kai Yang, Chih-Yu Hsu, Yen-Wei Jhou, and Jyh-Shen Tsay*

Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan PS-08 Exchange bias in NiFe/CoO/Fe2O3 trilayer X. Li(a), Y.-C. Chang(b), W.-C. Yeh(b), K.-W. Lin(b), *, R. D. Desautels(c), J. van Lierop(c), *, P. W. T. Pong(a), *

(a)Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong. (b)Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (c)Department of Physics and Astronomy, University of Manitoba, Winnipeg, R3T2N2, Canada

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PS-09 Chirality dependent vortex annihilation in asymmetric permalloy dots Deng-Shiang Shiu, Kuo-Ming Wu, Chao-Hsien Huang, Kao-Fan Lai, Jong-Ching Wu(a), and Lance Horng(a) Department of Physics, National Changhua University of Education, Changhua 500, Taiwan PS-10 Magnetic Properties of the NiFe Films Grown on the Ferroelectric BiFeO3 layer Chen-Hsu Chang, Yao-Sheng Hsu, Zheng-Wei Lin, Chin-Chung Yu Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan PS-11 Studies on Magnetism of Transition Metal Layers Grown on Graphene Chih-Heng Huang(a,b), Tzu-Hung Chuang(b), Chun-I Lu(b), Kun-Ta Lu(b), Chien-Chen Kuo(a,c), Der-Hsin Wei(b)

aProgram for Synchrotron Radiation and Neutron Beam Applications, National Sun Yat-sen University, Kaohsiung, Taiwan

bNational Synchrotron Radiation Research Center, Hsinchu, Taiwan

cDepartment of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan PS-12 Exchange coupling behaviour of the NiO/NiFe under exertions of bias voltages Li-Jing Wang, Zheng-Wei Lin, Chin-Chung Yu Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan PS-13 Tunnel Magnetoresistance in MTJs with embedded nanoparticles according particle’s size distribution A. Useinov(a,b,c), L.-X. Ye(b), N. Useinov(c), H.-H. Lin(a) and C.-H. Lai(b) (a)Department of Physics, National Tsing Hua University (NTHU), Hsinchu, Taiwan (b)Department of Materials Science and Engineering, NTHU, Hsinchu, Taiwan (c)Institute of Physics, Kazan Federal University, Kazan, Russian Federation

PS-14 Microstructure and magnetic properties of FePt/ (TiOC, TaC)/CrRu films Jai-Lin Tsai, Jie-Lin Tzeng, Keng-Chun Hu, Hsu-Kang Li, Zu-Yu Pan, Yuan-Shuo Chang, Chang-Chun Liao Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan PS-15 Effect of DO3 phase on high frequency permeability of Fe-Si powder cores Pyungwoo Jang(a), Gwangbo Choi(b) (a)College of Sci. & Eng., Cheong University, Cheongju , Korea (b)Changsung Corp., Namdong Industrial Area, Incheon, Korea PS-16 The structures and magnetism of Fe/FeO/Fe/FeV characterized by magnetometry and polarized neutron reflectometry Sara J. Callori(a), (b)*, Kai-Han Chao(c), Béla Nagy(d), László F. Kiss(d), László Bottyan(d), Ko-Wei Lin(c), and Frank Klose(b), (e)

(a) Department of Physics, California State University, San Bernardino, CA 92407, U.S.A (b) Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia (c) Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (d) Wigner Research Centre for Physics, H-1121 Budapest, Hungary (e) Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China

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Poster Session PT Nanoparticles and Bio-magnetism

Thursday Afternoon, Aug. 4th, 2016 Room: Multifunction Room Chair: Zung-Hang Wei/ National Tsing Hua University

PT-01 Synthesis of cobalt-based carbide particles by polyol process and their magnetic properties S. Fujieda, A. Yomogida, K. Shinoda, S. Suzuki Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan PT-02 Improving cell migration in wound healing using intracellular magnetic nanoparticles and magnetic force Wan-Ying Huang, Chao-Ming Su, Shyh-Liang Lu, Tzong-Rong Ger Department of Biomedical Engineering, University of Chung Yuan, Taoyuan, Taiwan PT-03 Synthesis and Characterization of Aqueous Magnetic Ferrofluid for Biomedical Application Jefunnie Matahum, Chao-Ming Su, Shyh-Liang Lou, Tzong-Rong Ger Department of Biomedical Engineering, Chung Yuan Christian University, Taoyuan, Taiwan PT-04 Magnetic Properties of Individual Magnetite Nanoparticles H. Mamiya(a), J. Nishigaki(b), M. Fukunaga(b), I. Furukawa(b), J. Cuya(b), and B. Jeyadevan(b) (a) National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan (b) The University of Shiga Prefecture, National Institute of Materials Science PT-05 Preparation of Magnetic Zeolite Materials and Application in Biomedical Studies V. Hovhannisyan, C. Y. Dong Department of Physics, National Taiwan University, Taiwan

PT-06 Biomolecular detection and capture in wave sheet ferromagnetic nanostructure C. R. Jeng, H. T. Huang, and Z. Wei Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

PT-07 Magnetic nanoparticle enhanced surface plasmon resonance for biosensing application H. T. Huang, T. S. Lin, and Z. Wei Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

PT-08 Magnetic properties of multilayered graphene oxide reduced in hydrogen atmosphere Y. Fujiwara, R. Mori, T. Tanaka, M. Jimbo , T. Kobayashi Graduate School of Engineering, Mie University, Tsu 514-8507, Japan School of Engineering, Daodo University, Nagoya 514-8507, Japan PT-09 Investigation of magnetic properties of Co0.2Zn0.8Fe2O4 nanoparticles for hyperthermia applications Sangjoon Lee, Sam Jin Kim, Chul Sung Kim Department of Physics, Kookmin University, Seoul 136-702, Korea

A-63

Poster Session PU Soft/Hard Magnetic Materials

Thursday Afternoon, Aug. 4th, 2016 Room: Multifunction Room Chair: Y.-T. Chen/ National Yunlin University of Science and Technology PU-01 PLD-made Nd-Fe-B thick film magnets deposited on Si substrates and their micromachining D. Shimizu(a), Y. Chikuba(a), A. Yamashita(a), M. Nakano (a), T. Yanai(a), R. Fujiwara(b), T. Shinshi(b), and H. Fukunaga(a) (a)Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan (b)Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama 226-8503, Japan PU-02 Magnetic Properties and Magnetocaloric effect in La1-xNdxFe10.5Si2.5 (x = 0.2, 0.4, 0.6) Alloys Wen-Zhe Nan(a), Tran Dang Thanh(a), Gnu Nam(b), Tae-Soo You(b), Seong-Cho Yu(a)

(a) Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea (b) Department of Chemistry, Chungbuk National University, Cheongju, 361-763, South Korea PU-03 Magnetic Iron implanted CuInSe2 thin film - A new room temperature diluted magnetic semiconductor Chih-Hao Lee, Li-Jung Liu and Yu-Sheng Chen Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan PU-04 Magnetic properties and thermal stability of amorphous CoFeSiBHf thin films M. Jimbo(a), Y. Fujiwara(b), T. Shimizu(a) (a)School of Engineering, Daido University, Nagoya 457-8530, Japan (b)Graduate School of Engineering, Mie University, Tsu 514-8507, Japan PU-05 Optimization of target composition in Nd-Fe-B film magnets prepared by high laser energy density H. Kondo, A. Yamashita, M. Nakano, T. Yanai, and H. Fukunaga Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan

PU-06 Development of anisotropic R-Fe-B powders with high performance Jinbo Yang， Jingzhi Han， Yingchang Yang School of Physics, Peking University, P.R. China PU-07 A study of the origin of large positive magnetostriction in Fe-B single-crystal films Tetsuroh Kawai(a), Mitsuru Ohtake(a) (b), and Masaaki Futamoto(a) (a)Faculty of Science and Engineering, Chuo University, Bunkyo-Ku, Tokyo 112-8551, Japan (b) Faculty of Engineering, Kogakuin University, Hachioji, Tokyo 192-0015, Japan PU-08 Microwave Hydrothermal Synthesis and Magnetic properties of Nanocrystalline Y3-

xGdxFe5O12 garnets for microwave circulator applications T.Ramesh (a), R.S.Shinde (b), S.R.Murthy (c) (a)Department of Physics, BVRIT Hyderabad College of Engineering for Women, Hyderabad, India. (b)Ferrite Laboratory, RRCAT, Indore, India. (c)Department of Physics, Geethanjali College of Engineering and Technology, Hyderabad, India. PU-09 The effect of Nd-Cu addition on the coercivity of hot-deformed magnet prepared with HDDR powder Haihang Wang(a), Renjie Chen(a), Wenzong Yin(a), Chaoxiang Jin(a), Zexuan Wang(a), Doo Lee(b), Aru Yan(a) (a)Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences (b)University of Dayton

A-64

PU-10 Combined effect of stress and magnetic field on domain in new Fe-based amorphous alloys Chengliang Zhao, Aina He, Anding Wang, Chuntao Chang, Xinmin Wang Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Key Laboratory of Magnetic Materials and Devices, and Ningbo Institute of Materials Technology &Engineering, Chinese Academy of Sciences, Ningbo 315201 China PU-11 Mössbauer studies of Ba3Zn2Fe24O41 Z-type hexaferrite Jung Tae Lim(a), Jung Chul Sur(b), In-Bo Shim(a), Chul Sung Kim(a)* (a) Department of Physics, Kookmin University, Seoul, 02707, South Korea (b) Department of Microelectronics and Display Tech., Wonkwang Univ., Iksan, 54538, South Krea PU-12 Spin reorientation of Li0.99Na0.01FePO4 with Mössbauer Spectroscopy Byung Ug Ko(a), Young Bae Lee(b), Bo Ra Myoung(a) and Chul Sung Kim(a)* (a)Department of Physics, Kookmin University, Seoul, 02707, South Korea (b)Department of Liberal Arts, Hanzhong University, Donghae, 25800, South Korea PU-13 High Energy Product and Coercivity enhancement of sintered Nd-Fe-B magnets by grain boundary diffusion Yang Zhao(a,b), Haibo Feng(a), Anhua Li(a), Minggang Zhu(a), Wei Li(a)

(a)Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081, P.R.China (b)School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P.R.China PU-14 High performance R-Fe-B die-upset magnets based on misch-metal alloys R. Lai (a), R. Chen (a), W. Yin (a), X. Tang (a), Z.

Wang; (a), D. Lee (b), A. Yan (a) (a) Rare Earth Magnetic Materials Laboratory, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, China. (b)University of Dayton, Dayton, OH, United States. PU-15 High rated current Fe-base metal core multilayer power inductor C. P. Wu, W. S. Ko, Y. T. Haung, Y. P. Wang, L. J. Wang and M. J. Tung Material and Chemical Research Laboratories Industrial Technology Research Institute, Taiwan PU-16 Effects of oxygen contents on the microstructures of high-performance SmCo 2:17-type sintered permanent magnet Wei Suna,b, Minggang Zhua,b, Yikun Fanga,b, Hongsheng Chena,b, Kuikui Songa,b, Nengjun Yua,b ,Wei Lia,b aFunctional Materials Research Institute, Central Iron & Steel Research Institute, Beijing 100081, China. bBeijing Engineering Laboratory of Advanced Metallic Magnetic Materials and Preparation Techniques, Beijing 100081, China. PU-17 Effect of phase structure on remanence thermal stability of Alnico8 alloysJ.T.Zhao,Y.L.Sun, Z.Liu, D.Lee,L.Liu, X.C.Feng, and A.R.Yan Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, ChineseAcademy of Sciences,Ningbo, 315201, China

A-65

5th August, Friday

A-66

Plenary Talk 8 William Gallagher

08:45-09:30, Friday, Aug. 5th, 2016 Room: 1st Lecture Hall Chair: Jung-Chun Huang/ National Cheng Kung University

The Development of Magnetic Tunnel Junction MRAM – from First Devices to Mbit Arrays to Emerging Spin-Torque Transfer MRAMs

William J. Gallagher

Taiwan Semiconductor Manufacturing Company, Hsinchu Science Park, Taiwan

This talk will review the history of the development of the magnetic tunnel junction devices and

materials for magnetic random access memory (MRAM). The magnetic tunnel junction device

itself was conceived in the mid-1970s along with applications for both sensors and memory.

However, it took 20 years for significant magnetoresistance response at room temperature to be

demonstrated (~11 to 18%) and serious device development to begin. The subsequent 20 years

have seen unimagined advances in both materials and magnetic device physics important for reading

in sensors and both reading and writing in memory. This talk will review the advances that have

been made particularly as they relate to the conception and emergence of spin-transfer torque MRAM.

Material, device, and array architecture choices will be discussed. Finally, examples of recent

MRAM demonstrations on an 8Mb MRAM platform [1] emphasizing either high speed operation [2]

or high temperature data retention [3] will be reviewed.

[1] Y. J. Lee, G. Jan, Y. J. Wang, K. Pi, T. Zhong, R. Y. Tong, V. Lam, J. Teng, K. Huang, R. R. He, S. Le, T. Torng, J. DeBrosse, T. Maffitt, C. Long, W. J. Gallagher, P. K. Wang, “Demonstration of chip level writability, endurance and data retention of an entire 8Mb STT-MRAM array,” 2013 International Symposium on VLSI Technology, Systems, and Applications (VLSI-TSA). [2] G. Jan, L. Thomas, S. Le, Y.-J. Lee, H. Liu, J. Zhu, J. Iwata-Harms, S. Patel, R.-Y. Tong, S. Serrano-Guisan, D. Shen, R. He, J. Haq, J. Teng, V. Lam, R. Annapragada, Y.-J. Wang, T. Zhong, T. Torng, and P.-K. Wang, “Achieving Sub-ns switching of STT-MRAM for future embedded LLC applications through improvement of nucleation and propagation switching mechanisms,”2016 VLSI-Technology Symposium, Paper 14.1. [3] M.-C. Shih, C.-Y. Wang, Y.­H. Lee, W. Wang, L. Thomas, H. Liu, J. Zhu, Y.­J. Lee, G. Jan, Y.-J. Wang, T. Zhong, T. Torng, P.-K. Wang, D. Lin, T.-W. Chiang, K.-H. Shen, H. Chuang, and W.J. Gallagher, “Reliability Study of Perpendicular STT-MRAM as Emerging Embedded Memory Qualified for Reflow Soldering at 260 C,” 2016 VLSI-Technology Symposium, Paper 14.1.

A-67

Session HA Magnetic Thin Films and Nanostructures IV

Friday Morning, Aug. 5th, 2016 Room: 3rd Lecture Hall Chair: Der-Hsin Wei/ National Synchrotron Radiation Research Center

Wondong Kim/ Korea Research Institute of Standards and Science

09:30-10:00 (Invited) HA-01 Investigation of the Origin of Ferromagnetic Signal Observed in Locally Functionalized Graphene Layers Wondong Kim Center for Nano-metrology, Division of Industrial Metrology, Korea Research Institute of Standards and Science 10:00-10:30 (Invited) HA-02 Measurement of interface Dzyaloshinskii-Moriya Interaction energy density in various ferromagnetic and heavy metal systems Chun-Yeol Youa,b aDepartment of Physics, Inha University, Korea bDepartment of Emerging Materials Science, DGIST, Korea 10:30-11:00 (Invited) HA-03 Magnetization Switching in Exchange-Coupled Systems Takeshi Seki(a),(b), Weinan Zhou(a), Koki Takanashi(a) (a)Institute for Materials Research, Tohoku University, Sendai, Japan (b)JST-PRESTO, Saitama, Japan

11:00-11:30 (Invited) HA-04 High-frequency spin dynamics of a magnetic antivortex Kristen S. Buchanan Department of Physics, Colorado State University, Fort Collins, CO, United States 11:30-11:45 HA-05 Growth of flexible NiFe2O4 thin films via Van der Waal heteroepitaxy Yugandhar Bitla(a) and Ying-Hao, Chu(a)(b)(c) (a) Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (b) Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (c) Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan 11:45-12:00 HA-06 Magnetic properties of RE:ZnO (RE=Sm,Eu,Gd,Dy,Ho,Er) thin films grown by pulsed-laser deposition Fang-Yuh Lo(a), Tsung-Chun Hsieh(a), Tzu-Lung Tseng(a), Kai-Chieh Chou, Yi-Chieh Ting(a), Yu-Ting Yeh(a), Wen-Tze Huang(a), Yung-Yuan Hsu(a), and Ming-Yau Chern(b) (a) Department of Physics, National Taiwan Normal University, 11677 Taipei City, Taiwan (b) Department of Physics, National Taiwan University, 10617 Taipei City, Taiwan

A-68

Session HB Spintronic Materials & Devices V

Friday Morning, Aug. 5th, 2016 Room: 1st Lecture Hall Chair: Hsiung Chou/ National Sun Yat-sen University

Mingzhong Wu/ Colorado State University

09:30-10:00 (Invited) HB-01 Deposition and Etch Process Equipment Capabilities for Embedded STT MRAM Mahendra Pakala Applied Materials Inc. 10:00-10:30 (Invited) HB-02 Initialization-free multilevel states driven by spin-orbit torque Switching Kuo-Feng Huang,a Ding-Shuo Wang,a Hsiu-Hau Lin,b and Chih-Huang Laia* aDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan bDepartment of Physics, National Tsing Hua University, Hsinchu, 300, Taiwan 10:30-11:00 (Invited) HB-03 Electrical detection of coherent spin precession in InAs 2DEG Joon Yeon Chang Center for Spintronics, Post-Si Semiconductor Institute (PSI)r Korea Institute of Science and Technology (KIST)

11:00-11:30 (Invited) HB-04 Photo-Spin-Voltaic Effect David Ellswortha, Lei Lua, Jin Lanb,c, Houchen Changa, Peng Lia, Zhe Wangc, Jun Hub, Bryan Johnsona, Yuqi Biana, Jiang Xiaoc, Ruqian Wub,c, and Mingzhong Wua†

aDepartment of Physics, Colorado State University, Fort Collins, CO 80523, USA. bDepartment of Physics and Astronomy, University of California, Irvine, CA 92697, USA. cDepartment of Physics, Fudan University, Shanghai 200433, China 11:30-12:00 (Invited) HB-05 Amorphous carbon: a smart material for spintronics applications H. S. Hsu* Department of Applied Physics, National Pingtung University, Pingtung 900, Taiwan, Republic of China

A-69

Session HC Advanced Powertrains for Electric Vehicles

Friday Morning, Aug. 5th, 2016 Room: 2nd Lecture Hall Chair: Cheng-Tsung Liu/ National Sun Yat-sen University

David G Dorrell/ University of KwaZulu-Natal

09:30-10:00 (Invited) HC-01 Overview of Electric Vehicle Machines – From Tesla to Tesla, and Beyond K.T. Chau* *Department of Electrical and Electronic Engineering, University of Hong Kong 10:00-10:30 (Invited) HC-02 High-Efficiency Magnetic Gear and Developing Magnetic-Geared Motor Kenji Nakamura*, Osamu Ichinokura Graduate School of Engineering, Tohoku University, Sendai, Japan

10:30-11:00 (Invited) HC-03 On the Use of the Frozen Permeability Method for Torque Separation in Synchronous Machines David G. Dorrell* Discipline of Electrical, Electronic and Computer Engineering, Faculty of Engineering, University of KwaZulu-Natal, Howard College, Durban, South Africa 11:00-11:30 (Invited) HC-04 Multiphysics Analysis for Traction Motors Considering Electromagnetics, Noise, Vibration and Harshness Chien-Hsing Li and Min-Fu Hsieh* Department of Systems and Naval Mechatronics Engineering, National Cheng Kung University, Tainan, Taiwan

A-70

1st August, Monday

B-1

AA-01

Nontrivial dynamic behavior of magnetic splitons: Strong inertial effects of magnetic skyrmions

Ki-Suk Lee

School of Materials Science Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Korea.

In a magnetic nanomaterial, spins often form a unique configuration such as a

whirlpool or a pulse shaped structure and they show nontrivial collective dynamics.

There is an elegant way to understand their collective dynamics of spins by considering

motions of magnetic solitions. Recently, one of fascinating magnetic structure known

as a magnetic skyrmion, which has topologically protected chiral spin texture, has been

attracted great attention because of their possible application to the future spintronic

devices by the benefit of its tiny size and high mobility [1,2]. It has been known that

the skyrmions can form at the room temperature through the chiral interaction,

Dzyaloshinskii-Moriya interaction (DMI), induced by the inversion-symmetry broken

at the interface between ferromagnetic and heavy-metal layers [3,4]. In this

presentation, we report micromagnetic simulation results on the strong inertial effects

of skyrmions driven by the time-varying spin-Hall effects. Finally, we propose the

manipulation method of the skyrmion dynamics to harness it as an information element

for the future spintronic signal processor and the non-volatile memory devices.

1. A. Fert.,V. Cros, and J. Sampaio, Skyrmions on the track Nat. Nanotechnol. 8, 152–6 (2013). 2. N. Nagaosa and Y. Tokura, Topological properties and dynamics of magnetic skyrmions Nat. Nanotechnol.

8, 899–911 (2013). 3. S. Woo et al., Observation of room temperature magnetic skyrmions and their current-driven dynamics in

ultrathin Co films, arXiv:1502.07376 (unpublished). 4. C. Moreau-Luchaire et al., Skyrmions at room temperature: from magnetic thin films to magnetic

multilayers, arXiv:1502.07853 (unpublished).

B-2

AA-02

Microwave spintronics. From fundamentals to applications Konstantin A. Zvezdin(a)(b)(c)

(a)A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilova st. 38, Moscow 119991, Russia

(b)Moscow Institute of Physics and Technology, Institutskiy per. 9, Dolgoprudny 141700, Russia

(c)Russian Quantum Center, Skolkovo, Moscow Region 143025, Russia

Modern semiconductor nanoelectronics in its development faces significant fundamental limitations associated with a sharp increase of the negative impact of the size effects arising from the increase in information density. In this context, the high attention is attracted to the spin-based nanoelectronics - spintronics. It is expected that spintronic devices that use the spin in addition to the charge during their operation will be able to overcome the fundamental problems of modern semiconductor nanoelectronics, which relay on the electron charge use only.

Beside the most well-known spintonic developments of STT MRAM, which is being prepared for release to the market by the largest microelectronic companies [1], there is another challenging direction of intensive research and development efforts in this area, which relates to the microwave spintronic, such as spin-torque nanooscillators (STNO) [2] and spin-diodes [3].

STNOs, flexible and agile sources of microwave signal, have demonstrated an impressive progress in terms of addressing such critical issues for practical application as output power and spectral linewidth [4]. In the talk an overview of the recent achievements in this area is provided, and the remaining fundamental and technological challenges are discussed.

Another fast growing research direction in the area of the microwave spintronics relates to the spin-diodes. It has been recently demonstrated that such devices may significantly overcome the sensitivity of the traditional semiconductor Schottky diode technology [5, 6], which makes spin-diodes to be a very promising technological platform for such industrical applications as ultrasensitive microwave detectors [7], ambient microwave energy harvesting and even for advence image recognition systems [8]. The recent advances and remaining challenges of this area are discussed. References

1. A. V. Khvalkovskiy et al., J. Phys. D: Appl. Phys. 46, 074001 (2013) 2. S. Kiselev et al., Nature 425, 380 (2003) 3. A. A. Tulapurkar et al., Nature 438, 339-342 (2005) 4. A. Dussaux, KAZ et al., Nat. Commun. 1, (2010) 5. Miwa et al., Nature Materials 13, 50-56, (2014) 6. Jenkins et al, Nature Nanotechnology, Doi: 10.1038/NANO.2015.295, (2016) 7. Fu et al., APL 105, 122406, 2014 8. Fu et al., JAP 117, 213902, 2015

B-3

AA-03

Quantum Transport in 2D Group-IV monolayers and TIs and their Potential Applications

Gengchiau Liang

Department of Electrical and Computer Engineering, National University of Singapore, Singapore e-mail: elelg@nus.edu.sg

Graphene, the first two-dimensional (2D) material, since its realization in 2004 has

spawned new possibilities for physicists and device engineers alike. The relativistic linear Dirac-bands with extremely high mobility of over 200000 cm2V-1s-1 and Klein tunneling in graphene makes it an excellent material for electron transport in THz high-speed and low-power atomically-thin devices of the future. The larger spin-orbit coupling (SOC), than in graphene, in later 2D-materials like Silicene and Germanene provides an additional control over the spin of an electron, which can possibly be used for non-volatile logic and zero-standby power application. Investigation of SOC in graphene has, however, taken a more prolific research direction with the recent discovery of topological insulating (TI) phase of matter in both 2D and three-dimensional (3D) systems. TI gets its unique advantage from having bulk band gap and SOC engendered spin-momentum locked helical Dirac 2D surface-states (1D edge-states) in 3D (2D) materials which are robust to non-magnetic impurities and disorders. The suppression of backscattering in both 2D and 3D TIs and weak electron-phonon coupling enables dissipationless surface (edge) transport. Therefore, topological insulators are posited to have gamut of applications ranging from interconnects and spintronics to optoelectronics, making them one of the most important contemporary material under investigation. Furthermore, due to strong SOC, the paring roles of 2D group IV materials are broken. As a result, the transmission can be maintained high between the different bands near the Dirac point while the transmission is still forbidden as the electron energy away from the Dirac point. Implementing this unique property, PIN structure is proposed and designed for a spin filter at room temperature. Our results show that the spin current polarization can achieve 60% at 300K compared, leading to the new avenue towards spintronic device applications.

B-4

AA-04

2D Materials and Devices for Spintronics: First-principles Studies

Qingyun Wu(a), Minggang Zheng(b), Sandhya Chintalapati(c), Lei Shen(d), Yuan Ping Feng(e,f)

(a) Department of Materials Science and Engineering, National University of

Singapore, Singapore (b) Data Storage Institute, A*STAR, Singapore

(c) Division of Physics and Applied Physics, Nanyang Technological University, Singapore

(d) Engineering Science Programme, National University of Singapore, Singapore (e) Department of Physics, National University of Singapore, Singapore

(f) Center for Advanced 2D Materials, National University of Singapore, Singapore

e-mail: phyfyp@nus.edu.sg

The key to success of spintronics is identification of suitable materials and evaluation of their performance in devices. While experimental studies take time and require a lot of resources, computational study, particularly first-principles calculations, is playing an important role. We have been using such methods to investigate a series of materials as well as conceptual design of spintronic devices. In earlier studies, [1,2] we proposed spin logic gates based on zigzag graphene nanoribbons. However, some issues still remain for graphene based spintronic devices, and one of them is the low efficiency of spin-injection from a metal lead to graphene. Through first-principles calculations, we found that spin injection efficiency from a metal lead to graphene can be enhanced by using a hexagonal boron nitride (h-BN) between the electrode and graphene. [3] We also investigated transport property of phospherene nanoribbons (PNRs). In contrast to graphene and MoS2 nanoribbons, the carrier transport channels under low bias are mainly located in the interior of both armchair and zigzag PNRs, and immune to small amounts of edge defects. High on/off ratio dual-gate FET can be achieved using PNRs. [4] Our recent calculations reveal that phospherene can be made magnetic by an interplay of vacancy and strain, even though neither P vacancy nor external strain alone results in magnetism in phosphorene. When either a biaxial strain or a uniaxial strain along the zigzag direction of phosphorene containing P vacancies reaches 4%, the system favours a spin-polarized state with a magnetic moment of 1 B per vacancy site. [5] [1] M G Zeng et al., Appl. Phys. Lett., 98, 092110 (2011). [2] M G Zeng et al., Phys. Rev. B, 83, 115427 (2011). [3] Q. Y. Wu, et al., Phys. Rev. Appl. 2, 044008 (2014). [4] Q. Y. Wu, et al., Phys. Rev. B, 92, 035436 (2015). [5] S. Chintalapati et al., Appl. Phys. Lett. 107, 072401 (2015).

B-5

AA-05

First-Principles Analyses of Electronic Structure of Multiferroic Nd doped BiFeO3 Solid Solution

Peng, Yi-Ting (a), Tu, Chi-Shun (b) Hsiao, Ching-Hung (a), Ouyang, Hao (a)

(a) Materials Science and Engineering, National Tsing Hua University, Hsinchu City,Taiwan.

(b) Physics, Fu Jen Catholic University, New Taipei City, Taiwan. e-mail: orange3058@yahoo.com.tw

BiFeO3(BFO) and Bi0.95Nd0.05FeO3 (B-Nd) ceramics were prepared by solid state reaction method[1]. In the perovskite type structure ABO3, the substitution of Bi3+ by Nd3+ was identified on the A-site[2]. Crystal refinememts(from XRD in Fig.1(a)) and STEM in Fig.1(b)/HRTEM(Scanning and High-resolution transmission electron microscopy)with the multislice methods reveal a R3c space group with lattice parameters of aBFO= 5.48 Å,αBFO= 59.90

,and aB-Nd= 5.64 Å, αB-Nd=59.82 for BFO and

B-Nd, respectively. For Nd doped BFO, the photovoltaic effect was markedly improved ,where the maximum power-conversion efficiency increased around 2 order due to the reduced optical band gap, and, reduced leakage current density as Nd substitutes the Bi sites, resulting in a structural distortion, reducing the Bi deficiency [3]. The optically measured band gap are 2.24eV and 2.204eVfor BFO and B-Nd, which are consistent reasonably well with the calculated results based on Vienna ab initio simulation package(VASP) [4,5] following L(S)DA+U methods. In Figs. 1(c) and (d), the calculated band gap of B-Nd is 2.091eV which is smaller than the simulated value 2.271eV of BFO. [1] C. S. Tu, C.-M. Hung et al., J. Appl. Phys. 114, 124105 (2013) [2] G. L. Yuan,and Siu Wing Or et al., Appl. Phys. Lett. 89, 052905 (2006) [3] Yohei Ukai, Shuhei Yamazaki et al., Jpn. J. Appl. Phys. 51 09LE10 (2012) [4] G. Kresse and J. Hafner, Phys. Rev. B 48, 13 115 (1993). [5] G. Kresse and J. Furthmuller, Phys. Rev. B 54, 11 169 (1996).

FIG.1(a)XRD of B-Nd(b)High resolution Dark-field image (c)band structure of BFO (d)band structure of B-Nd

B-6

AA-06

Interfacial Dzyaloshinkii-Moriya Interaction Induced Domain Wall Depinning Anomaly

H. K. Teoh(a), S. Goolaup(a), W. S. Lew(a) (a)School of Physical and Mathematical Sciences,

Nanyang Technological, University, 21 Nanyang Link, Singapore 637371

Domain wall positional control is vital for the realization of domain wall based magnetic memory and logic devices [1,2]. In this work, we theoretically and numerically demonstrated that the presence of interfacial Dzyaloshinkii-Moriya interaction [3] leads to different static depinning field for Neel domain walls with the same handedness at a notched magnetic nanowire. An expression which relates the difference in static depinning field, Δ to the notch geometry is derived :

Δ4

0tan

1tanh

sec

4tan

1tanh

1

4 1 1

1

. Our theoretical estimate

compares well with numerical results. In addition, the dynamics of domain wall depinning is studied with simulation. The depinning mechanism is explained with the variation of local effective field acting on domain wall profiles due to interfacial Dzyaloshinkii-Moriya interaction.

(a) (b)

Fig. 1: (a) shows difference in depinning field for ↓↑ and ↑↓ Neel DW configuration as a function of notch angle θ (b) shows difference in depinning field for ↓↑ and ↑↓ DW configuration as a function of notch depth to nanowire width ratio for different type of notches. Dotted lines represent simulation data while continuous lines are theoretical estimate. [1] S. S. Parkin, M. Hayashi, and L. Thomas, “Magnetic domain-wall racetrack memory,” Science 320, 190–194 (2008) [2] D. A. Allwood, G. Xiong, C. Faulkner, D. Atkinson, D. Petit, and R. Cowburn, “Magnetic domain-wall logic,” Science 309, 1688–1692 (2005). [3] I. Dzyaloshinsky, Journal of Physics and Chemistry of Solids 4, 241 (1958)

B-7

AA-07

Shape-dependent Skyrmion dynamics under spin-orbit torque

I. Purnama, G. W. Shiguang, W. L. Gan, and W. S. Lew

School of Physical & Mathematical Sciences, Nanyang Technological University

The quest to create hi-performance novel magnetic memory devices has led to significant advances on the topic of spin-orbit torques as well as magnetic skyrmions in recent years [1-2]. From the application perspective, the inclusion of spin-orbit torques in magnetic-based devices has led to fast- and energy efficient device operation, whereas research on magnetic skyrmions has led to the conception of novel memory and logic devices. In this work, we show that the presence of spin orbit torques in a skyrmion-enabled film result in the emergence of a force whose direction depends on the magnetization configuration of the skyrmion itself. By expanding the method used by Thiele, we show that for several skyrmion types, the interplay between the spin orbit force and the Magnus force makes it possible for the skyrmion to move against the directions of the conduction and the spin current. With this in mind, the modified Thiele equation with spin orbit torques can then be written as: SHED FvvG 0 (1) Which gives us:

222 DG

FDv

rSHEr

x and

222 DG

FGv

D

Gv

rSHEr

xr

y

(2)

[1] A. V. Khvalkovskiy, et al., Phys. Rev. B 87, 020402R (2013). [2] S. Woo, et al., arXiv:1502.07376.

Figure 1 (a) Plot showing the calculated values of the forces from the spin orbit torques that are received by a radial-type skyrmion with a diverging spins and a -z core. Inset shows the directions of the axis of references. (b) Schematics showing the relation between the directions of the conduction electron flow, the force from the SOT, as well as the skyrmion motion for radial-type skyrmion with diverging spins.

B-8

AA-08

Fig. 1. XRD pattern indicating vanishing (210) l

Bi3+ Doping Induced Suppression of Spin Flop Transition in DyMnO3

D. Paul Joseph(a), N. Pavan Kumar(a), J.W. Lin(c) , W.C. Chen(b), J.G. Lin(b)*

(a) Department of Physics, National Institute of Technology, Warangal, Telangana State, 506004, India.

(b) Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.

(c) National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan. * Corresponding author E-mail: jglin @ ntu.edu.tw

Doped perovskite manganites [1] have attracted renewed attention due to

scientific interest and prospective novel device applications [2]. Substitution of ‘Dy3+’ site with isovalent ‘Bi3+’ in DyMnO3 without changing effective ‘Mn’ valence could generate the A-site cationic mismatch to introduce a “chemical pressure”, leading to an enhanced distortion of perovskite structure [3], which has not been explored widely. Our experiments indicate formation of Bi2O3 impurity when the doping is greater than 2%. In this work, effect of ‘Bi’ doping in Dy1-xBixMnO3 is studied on the variation of structural and magnetic properties. It is observed that the intensity of (210) plane of orthorhombic structure decreases with ‘Bi’ content and vanishes at x = 0.15 (Fig. 1). In the magnetization data, the ZFC-FC curves become irreversible upon doping with ‘Bi’. At 2 K, a spin flop like transition is observed in DyMnO3 and it gradually decreases with Bi doping with an enhancement of HC and Mr, indicating a change from soft to hard magnet contrary to the case of ‘Bi’ doped LaMnO3 [4]. Specific heat capacity data implies a ferroelectric transition Tlock to vanish upon doping with ‘Bi’. In addition, the FC magnetization data fitted well with a phenomenological model and the related magneto-caloric effects will be discussed. [1]. G. H. Jonker and J. H. Van Santen, Physica, 16 (1950) 337. [2]. N. Hur, S. Park, P. A. Sharma, et al., Nature (London) 429, (2004) 392. [3]. M. Gajek, M. Bibes, et al., Phys. Rev. B, 75, (2007) 174417. [4]. D. Paul Joseph, J.W. Lin, et al., JMMM, 2016 (In Press)

B-9

AB-01

Advanced Spintronic Materials Based on Ordered Alloys

Koki Takanashi

Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan e-mail: koki@imr.tohoku.ac.jp

Materials used for spintronic devices should satisfy the following requirements:

- High spin polarization, leading to high efficiency in spin injection and high

magnetoresistance.

- High magnetic anisotropy, leading to perpendicular magnetization and thermal

stability of magnetization at reduced dimension.

- Proper damping constant, leading to the optimization of the influence of spin

transfer torque.

It would be the best to find a universal material that satisfies all these requirements

together; however, it is not so easy. Starting from a material that satisfies one of each,

usually, the way to extend the function by some modification of the material or to

combine those materials is adopted. We are interested in ordered alloys for spintronics,

because some of ordered alloys show excellent functionalities such as high spin

polarization and high magnetic anisotropy, and they are promising for the application

to spintronics.

Our group has been working on half-metallic Heusler alloys with high spin

polarization, and demonstrated high CPP-GMR [1-3], which will be promising for the

application to read heads in next-generation HDD. CPP-GMR devices with half-

metallic Heusler alloys also show high performance as spin torque oscillators (STOs)

[4,5] because of their low magnetic damping.

In my talk, I will show an overview on our recent work on ordered alloys, especially

Heusler alloys for spintronics, and future prospect for a universal material which

satisfies all the requirements together.

[1] T. Iwase et al., Appl. Phys. Exp., 2, 063003 (2009). [2] Y. Sakuraba et al., Appl. Phys. Lett. 101, 252408 (2012). [3] T. Kubota et al., Appl. Phys. Exp., 8, 063008 (2015). [4] T. Seki et al., Appl. Phys. Lett. 105, 092406 (2014).

[5] T. Yamamoto et al., Appl. Phys. Lett. 106, 092406 (2015).

B-10

AB-02

Spin Currents in Antiferromagnets

Axel Hoffmann(a), Wei Zhang(a), Stephen M. Wu(a), Hilal Saglam(a,b), Joseph Sklenar(a,c), M. Benjamin Jungfleisch(a), Wanjun Jiang(a), Yaohua Liu(a),

John E. Pearson(a), Suzanne G. E. te Velthuis(a), J. Samuel Jiang(a), Anand Bhattacharya(a), John B. Ketterson(c), Frank Freimuth(d), Yuriy Mokrousov(d),

Amit KC(e), Pavel Borisov(e), David Lederman(e),

(a)Mater. Science Division, Argonne National Laboratory, Argonne, IL 60439, USA (b)Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA

(c)Dep. of Physics and Astronomy, Northwestern Univ., Evanston, IL 60208, USA (d)Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany

(e)Dep. of Phys. and Astron., West Virginia Univ., Morgantown, WV 26506, USA e-mail: hoffmann@anl.gov

Harnessing spin currents is a promising pathways towards low-power electronics [1]. Towards this end it has recently been recognized that antiferromagnetic materials can play a more active role beyond their traditional use for providing a reference magnetization direction via exchange bias. Namely, antiferromagnets may be conduits for spin currents, as well as, actively enable spin current generation and detection. With respect to the later, we recently demonstrated spin current generation both via spin Hall effects in conducting antiferromagnets and spin Seebeck effects in insulating antiferromagnets. Using CuAu-I-type metallic antiferromagnets (PtMn, IrMn, PdMn, and FeMn) we showed by using spin pumping that these alloys have significant spin Hall effects, which in the case of PtMn become comparable to the ubiquitously used Pt [2]. The spin Hall angles increase for the alloys with heavier element; a behavior that is well reproduced by first-principle calculations of the spin Hall conductivities based on intrinsic spin Hall effects. Furthermore, the calculations suggest pronounced anisotropies of the spin Hall conductivities, which we tested using spin transfer torque ferromagnetic resonance measurements using epitaxially grown antiferromagnetic films [3]. We observe that indeed the spin Hall conductivity is maximized for different growth orientations (a-axis for PtMn and PdMn, and c-axis for IrMn) in accordance with the first principle calculations. Lastly, using epitaxial MnF2/Pt bilayers, we observe spin Seebeck voltages with distinct features due to the well-known spin-flop transition in MnF2 [4].

This work was supported by the U.S. DOE, Office of Science, Materials Sciences and Engineering Division, DFG, the West Virginia Higher Education Policy Commission, U.S. NSF, and the WVU Shared Research Facilities. [1] A. Hoffmann and S. D. Bader, Phys. Rev. Appl. 4, 047001 (2015). [2] W. Zhang, et al., Phys. Rev. Lett. 113, 196602 (2014). [3] W. Zhang, et al., Phys. Rev. B 92, 144405 (2015). [4] S. M. Wu, et al., Phys. Rev. Lett., in press (2016); arXiv:1509.00439.

B-11

AB-03

Soliton-like magnetic domain wall motion induced by the interfacial Dzyaloshinskii-Moriya interaction

Teruo Ono

Institute for Chemical Research, Kyoto University, Gokasho, Uji, Japan e-mail: ono@scl.kyoto-u.ac.jp

Topological defects such as magnetic solitons, vortices, Bloch lines, and skyrmions start to play an important role in modern magnetism due to their extraordinary stability which can be hailed as future memory devices. Recently, novel type of antisymmetric exchange interaction, namely the Dzyaloshinskii-Moriya interaction (DMI), has been uncovered and found to influence on the formation of topological defects. Exploring how the DMI affects the dynamics of topological defects is therefore an important task.

Here we investigate the dynamics of the magnetic domain wall (DW) under a DMI by developing a time-of-flight measurement scheme which allows us to measure the DW velocity for magnetic fields up to 0.3T. For a weak DMI, the trend of DW velocity follows the Walker’s model which predicts that the velocity of DW increases with field up to a threshold (Walker field) and decreases abruptly. On the other hand, for a strong DMI, velocity breakdown is completely suppressed and the DW keeps its maximum velocity even far above the Walker field. Such a distinct trend of the DW velocity, which has never been predicted, can be explained in terms of magnetic soliton, of which topology can be protected by the DMI. Importantly, such a soliton-like DW motion is only observed in two dimensional systems, implying that the vertical Bloch lines (VBLs) creating inside of the magnetic domain-wall play a crucial role [1].

This work was partly supported by JSPS KAKENHI Grant Numbers 15H05702, 26870300, 26870304, 26103002, 25·4251, Collaborative Research Program of the Institute for Chemical Research, Kyoto University, and R & D Project for ICT Key Technology of MEXT from the Japan Society for the Promotion of Science (JSPS). [1] Y. Yoshimura, K.-J. Kim, T. Taniguchi, T. Tono, K. Ueda, R. Hiramatsu, T. Moriyama, Ke. Yamada, Y. Nakatani, T. Ono, Nature Physics (2015) doi:10.1038/nphys3535.

B-12

AB-04

Spin current coupled with dynamical magnetization

Kazuya Ando

Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan

The collective excitation of localized spins coupled by the magnetic dipole and quantum exchange interactions is called spin waves or, in quantized form, magnons. This quasiparticle, associated with the elementary magnetic excitation, is responsible for a flow of spin angular momentum, a spin current, in magnetic insulators. The spin-carrier can be converted from magnons to conduction electrons at magnetic/nonmagnetic interfaces through dynamical spin exchange coupling between magnetization and conduction electron spins. This spin-carrier conversion enables dynamical generation of spin currents from magnetic insulators, enabling to explore the physics of spin current in condensed matter [1,2].

Recently it has been demonstrated that the dynamical spin-current generation is

enhanced in the presence of magnon splitting. However, the role of magnon interactions in the spin-current emission is still not well understood. Here, we show that the enhanced spin-current emission is enabled by spin-damping tuning triggered by the redistribution of magnons. Our direct measurements of the spin damping demonstrate that the stabilized enhancement of the spin-current emission is enabled by the long lifetime of the dipole-exchange secondary magnons created at the inflection point of the dispersion curve, where the negative dipolar dispersion is compensated by the positive exchange dispersion. We demonstrate, furthermore, that the spin-current emission can be enhanced even in the absence of the magnon splitting; we found enhanced spin-current emission triggered by scattering processes that conserve the number of magnons. These findings demonstrate the crucial role of magnon lifetimes in spintronic devices, opening a way for controlling nonlinear spin-current emission through spin-damping tuning. [1] H. Sakimura, T. Tashiro, and, K. Ando, Nature Communications 5, 5730 (2014). [2] T. Tashiro, S. Matsuura, A. Nomura, S. Watanabe, K. Kang, H. Sirringhaus, and K. Ando, Scientific Reports 5, 15158 (2015).

B-13

AB-05

Magnetism modulation of Fe/ZnO heterostructure explored by in-situ x-ray absorption spectroscopy and

electrical characterization

Shu-Jui Chang (a), Shao-Hua Lo (a) , Po-Chun Chang(b), Wen-Chin Lin (b) , and Yuan-Chieh Tseng* (a)

(a) Dept. Materials Science & Engineering, National Chiao Tung University,

Hsinchu, Taiwan. (b)Dept. Physics, National Taiwan Normal University, Taipei, Taiwan.

e-mail: yctseng21@mail.nctu.edu.tw

Electrical control of magnetism is critical to the spintronic applications. For an oxide-ferromagnetic heterostructure, spin-orbital torque (SOT) plays an important role to control the magnetization switching by current injection, which originates from the structural inversion asymmetry of the two dissimilar materials. In this work we demonstrate the control of interface chemical state using a current heating process across an Au/Fe/ZnO/Au heterostructure device. Meanwhile, a synchrotron setup capable of performing x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) with simultaneous electrical control characterizations was employed, which was to monitor the modifications of interface state during the current heating. From MOKE measurement we observed a reversible voltage-induced change of magnetic coercivity (Hc) of the device (Fig.1(a)), and the Hc value was found to depend on the current-heating condition (Fig.1(b)). Voltage-dependent Fe L2/L3 XMCD (Fig. 1(c)) was obtained in this device structure, suggesting the change of the spin-electronic state of the Fe layer as a result of the modified hybridization state with ZnO upon current-heating. With the unique x-ray setup the element specific anomalous Hall effect (AHE) was also measured to explore the complex transport/spin-state correlation of the ferromagnetic-oxide interface.

Fig.1(a) MOKE hysteresis loops measured at RT at various applied voltages. (b)Current-heating dependency of the Hc values, where the Au/Fe/ZnO/Au device was annealed by different voltages (i. e. current-heating) for as-deposited condition. (c) Voltage-dependent XMCD of the Au/Fe/ZnO/Au device.

B-14

AB-06

Magnetic Property of Fullerene C20 : A First-Principles Study

Icuk Setiyawati and Yu-HuiTang*

Department of Physics, National Central University, Jhong-Li, Taiwan

Contact: yhtang@cc.ncu.edu.tw

From the production in the gas phase by Prinzbach[1], the C20 as the smallest fullerene has been

attracted considerable attention among scientists. In the following year, Wang et al[2]sucessfully

synthesized the solid phase of C20 using ion beam irradiation method and found that the fullerene C20

behave as the building block of hexagonal crystal. What more interesting is the existence of

magnetism in carbon materials which is experimentally investigated, i.e chains of interacting radicals,

carboneous substances with mixture sp2 and sp3 coordinated atoms, nanographite, nanodiamond,

carbon nanofoams, as well as TDAE-C60 [3]. These evidences supports the theoretical predictions

that electronic instabilities in pure carbon may give rise to ferromagnetic property even at room

temperature.

To investigate the underlying mechanism of the magnetism C20 cage structure, we employed the

density functional theory (DFT) within the nonequilibrium Keldysh Green’s function (NEGF)

formalism to study the spin-polarized density of states of the isolated nonmagnetic C60, which are

truncated by the mixture of pentagons and hexagons as shown in Fig. 1(a), and of the isolated

magnetic C20 cage and C15 bowl-like molecules, which exhibit purely pentagon-bunching structure as

shown in Fig. 1(b) and (c). For the C15 bowl-like structures, the spin-polarized molecular levels are

mainly contributed by those C atoms on the zigzag edge, while, for the C20 cage structure, all

molecular levels are spin-polarized resulting from the zigzag boundaries between pentagons which

also verified using plane waves-DFT (Quantum Espresso). Such zigzag-boundary induced magnetic

properties of C20 cage and C15 bowl-like molecule can be analog to the graphene nanoribbon with

zigzag edges [4]. Moreover, the non-magnetic and insulating properties of C60 and C20 bowl-like

molecules can be attributed to the mixture of hexagon and pentagons.

The structural stability of C20 cage undergoes changes (i.e compressed) after optimization which

still retain spin polarized density of states. (Contract No. NSC 102-2112-M-008-004-MY3)

[1] H. Prinzbach et al., Nature (London) 407, 60 (2000).

[2] Z. Wang et al., Phys. Rev. Lett A 280, 351-356 (2001).

[3]M. Tatiana (Magnetism of Carbon-Based Materials).,Studies of High-Tc Superconductivity, vol.44-45 edited by A.

Narlikar (2001).

[4] K. Nakada et al., Phys. Rev. B 54,17954-17961 (1996).

(a) (b) (c

B-15

AB-07

Van der Waal epitaxy: a new perspective for flexible spintronic devices

Ping-Chun, Wu(a)(f), Ping-Fan, Chen(b), Chun-Hao Ma(c), Ha Tai Duy(c), Kun-Hong Wu(d), Qing-He(e), Yi-Chun Chen(d), Chun-Fu Chang(f), Ying-

Hao, Chu(a)(b)(c)

(a) Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

(b) Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (c)Department of Electrical Engineering, National Tsing Hua University, 30013 Hsinchu, Taiwan

(d) Department of Physics, National Cheng Kung University, Tainan City 701, Taiwan (d) Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan

(e) Department of Physics, Durham University, Durham DH1 3LE, United Kingdom (f) Max Planck Institute for Chemical Physics of Solids, Noethnitzerstr. 40, 01187 Germany

e-mail: bjwu.mse03g@nctu.edu.tw Magnetite (Fe3O4) is a promising candidate for spintronic devices due to its high

spin-polarization at Fermi level[1], high Curie temperature[2] and high conductivity[3]. In this work, to demonstrate Fe3O4 for flexible spintronics, we establish Fe3O4 on flexible and transparent muscovite substrates, shown in Fig. 1 and Fig. 2. The crystal structure and epitaxial relationship are established by a combination of reflection high energy electron diffraction, high-resolution x-ray diffraction(Fig. 3) and Raman spectroscopy. The chemical compositions are examined by x-ray photoemission spectroscopy, soft x-ray absorption spectra and x-ray magnetic circular dichroism. The electrical and magnetic properties are also characterized to confirm that the Fe3O4/muscovite heterostructure preserved the original properties of Fe3O4. All these evidence strongly suggests that Fe3O4/muscovite heterostructure can be utilized as flexible spintronic devices.

[1] De Groot, R. A., et al. Physical Review Letters 50.25 (1983) [2] Miles, P. A., W. B. Westphal., et al. Reviews of Modern Physics 29.3 (1957) [3] Rosencwaig, A. Canadian Journal of Physics 47.21 (1969)

B-16

AB-08

Spin Transport Calculation in Novel nm-scale Magnetic Junctions

Yu-Hui Tang

Department of Physics, National Central University, Jhong-Li, Taoyuan, Taiwan e-mail: yhtang@cc.ncu.edu.tw

Recently, our theoretical researches focus on searching for novel nm-scale ferromagnetic/barrier/ferromagnetic (FM/B/FM) magnetic tunnel junctions (MTJs) with superior spin transport properties by choosing semiconductor [1], spin-filter material [2], and single molecule [3] as the central barriers, which may inspire further experimentations in spintronics applications. However, the main difficulty in the spin transport study of these complex heterojunctions is the lack of reliable simulation tools. We have developed the tight-binding model, derived the general expression of non-collinear spin torque effect, and tested various kinds of first-principles spin-polarized transport calculation tools for conventional MgO-based MTJs [4,5], Au/Oligothiophene/Au junction [6], and single-molecule magnetic junctions with different linker and central molecules. Finally, we’ve successfully combined the first-principles calculation with the tight-binding model and the non-equilibrium Keldysh Green’s function method not only to calculate the collinear spin polarized current densities but also to further predict the non-collinear spin torque effect via our newly derived general expressions. This in turn may resolve the current self-consistence difficulties of first-principles spin-polarized transport calculations for complex heterojunction structures in non-collinear magnetic configuration. (Contract No. NSC 102-2112-M-008-004-MY3)

[1] Y. –H. Tang, F. –C. Chu, and N. Kioussis, Sci. Rep. 5, 11341 (2015).

[2] Y. –H. Tang and F. –C. Chu, J. Appl. Phys. 117, 093901 (2015).

[3] Y. –H. Tang et al., J. Phys. Chem. C 120, 692 (2016)

[4] Y. –H. Tang et al., Phys. Rev. Lett. 103, 057206 (2009).

[5] Y. –H. Tang et al., Phys. Rev. B 81, 054437 (2010).

[6] Y. –H. Tang et al., J. Phys. Chem. C 115, 25105 (2011)

B-17

AC-01

Microwave assisted switching and its application to 3D recording system

N. Kikuchi(a), S. Okamoto(a), H. Suto(b), Y. Nakayama(c),(d), O. Kitakami(a), K. Kudo(b), T. Nagasawa(b), T. Kanao(b), K. Mizushima(b), R. Sato(b),

T. Shimatsu(c), (d)

(a)Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan

(b)Corporate Research and Development Center, Toshiba Corp., Kawasaki, 212-8582, Japan

(c)Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, 980-8578, Japan

(d)Research Institute of Electrical Communication, Tohoku University, Sendai, 980-8577, Japan

e-mail: kikuchin@tagen.tohoku.ac.jp

Microwave assisted magnetic recording (MAMR) is one of the promising candidates for further high density magnetic recording system. In MAMR, precessional motion of magnetization is resonantly excited by rf fields with GHz frequency to switch magnetization in reduced writing fields. Figure 1 shows switching field of a Co/Pt multilayer dot array measured under application of rf field of 500 Oe in amplitude as a function of rf field frequency frf. [1] The switching field decreases with increase of frf linearly up to the critical frequency fc = 11 GHz and the assistance effect vanishes for higher frequency. This frequency dependent transition behaviour is a nature of microwave assisted switching (MAS) and allows to switch magnetization of specific layer with different fc in multilayered media selectively. Thus, we have proposed three dimensional (3D) recording system based on MAMR, which is composed of antiferromagnetically coupled (AFC) multilayered media and a spin-torque oscillator (STO) as a rf field source and a reader. [2-4] We have successfully demonstrated layer selective switching on a double layered nanodot by adjusting rf field frequency as the optimum ones for each layer. [4] More details of MAS effect in various structures including AFC granular films will be also discussed. [1] M. Furuta et al., APEX 6, 053006 (2013). [2] T. Yang et al., J. Appl. Phys. 114, 213901 (2013). [3] H. Suto et al., Nanotechnology 25, 245501 (2014). [4] H. Suto, et al., Phys. Rev. Appl. 5, 014003 (2016).

Fig. 1 switching field of Co/Pt multilayer dots under application of rf field of frequency frf. The circles indicate the result of LLG calculation.

B-18

AC-02

Control of microstructure of FePt-X (001) films for HAMR through interface modification and doping

Jingsheng Chen

Department of Materials Science and Engineering, National University of Singapore, Singapore

The main challenge of the application of L10 FePt thin films as magnetic recording media is the simultaneous fabrication of FePt (001) thin films with high perpendicular anisotropy and small grain size. L10 FePt (001) granular films with grain size of 5-6 nm were achieved on MgO underlayer by doping C and Ag.1-4 However, RF sputtering of the insulating MgO underlayer layer is not preferred for industrial applications due to its low deposition rate and particle contamination on the media surface. The large opening-up of in-plane hysteresis loop was observed in the FePt film grown on polycrystalline MgO underlayers that would increase the switching field distribution and thus reduce the signal-to-noise ratio. We found that the large opening-up of the in-plane hysteresis loop was caused by the smaller surface energy of MgO (1.1 J/m2) with comparison with FePt (2.9 J/m2) which resulted in a large contact angle between FePt grain and MgO and is not favorable for epitaxial growth.5-6 The situation became worse when polycrystalline MgO underlayer was used. Any small deviation of texture of underlayer and roughness change will cause deviation of the crystal orientation of FePt overlayer from film normal (001) orientation. Based on this, we proposed to use TiN and TiON as intermediate layers or underlayers to promote the (001) texture of FePt film and grain isolation.6, 7 The highly (001) textured FePt-SiO2-C films with high magnetocrystalline anisotropy and in-plane hysteresis loops with small opening-up and well-isolated grain with size of 5.7 0.9 nm. With introducing new doping materials, we have developed columnar structured FePt-X (001) films with well-isolated small grains and large coercivity on TiON intermediate layer. The FePt grains with size of 5.6 nm showed very good columnar structure with aspect ratio of around 2.6. The out-of-plane coercivity of the film deposited at 500oC is as high as 23.2 kOe. 8

Reference 1. J. S. Chen, B. C. Lim, J. F. Hu, B. Liu, G. M. Chow, G. Ju, “Low temperature deposited L10 FePt(001) films with

high coercivity and small grain size” Appl. Phys. Lett. 91, 132506 (2007).

2. J. S. Chen, B. C. Lim, J. F. Hu, G. M. Chow, G.Ju, “Microstructure and magnetic properties of L10 FePt-C(001)

textured nanocomposite films grown on different intermediate layer” J. Phys. D: Appl. Phys. 41, 205001 (2008).

3. O. Mosendz, S. Pisana, J. Reiner, B. Stipe, D. Weller, “ High density temperature assisted recording on granular

FePt-AgC media” CF-05, 56th Annual conference on magnetism and magnetic materials, 30 Oct.-3 Nov. 2011,

Scottsdale, AZ.

4. L. Zhang, Y. K. Takahashi, K. Hono, B. C. Stipe, J.-Y. Juang, and M. Grobis, “L10 -ordered FePtAg-C granular thin

film for thermally assisted magnetic recording media,” J. Appl. Phys., vol. 109, 07B703, (2011).

5. H. H. Li, J. F. Hu, G. Ju, G. M. Chow, J. S. Chen, “Effects of CrRu-SiOX underlayer on the microstructure and

magnetic properties of FePt-C thin film” J.Appl.Phys. 109, 07A736 (2011)

6. H. H. Li, K. F. Dong, Y. G. Peng, G. Ju, G. M. Chow, J. S. Chen, “High coercive FePt and FePt-SiNx (001) films

with small grain size and narrow opening-up of in-plane hysteresis loop by TiN intermediate layer” , J. Appl. Phys.

110, 043911 (2011).

7. H. H. Li, K. F. Dong, Y. G. Peng, G. Ju, G. M. Chow, J. S. Chen, “Highly (001) textured L10 FePt-SiO2-C films

with well-isolated small grains by using TiON intermediate layer” Applied Physics Express, 6, 075502 (2013).

8. K. F. Dong, H. H. Li, Y. G. Peng, G. Ju, G. M. Chow, J. S. Chen, “ L10 FePt-X films with high aspect ratio columnar

structure” Appl. Phys. Lett., 104, 192404 (2014).

B-19

AC-03

Media Design and Challenges for Heat-Assisted Magnetic Recording for 2Tbpsi and beyond

Eric K.C. Chang, Pin-Wei Huang, Hassib Amini, Yingguo Peng, Li Gao, Yinfeng

Ding, Timothy Klemmer, Xiaobin Zhu, Alexander Q. Wu, Yukiko Kubota, Jan-Ulrich

Thiele, Ganping Ju

Seagate Fremont

E-mail: Eric.KC.Chang@Seagate.com

The demand for greater storage capacity is fueled by current explosive usage of social media, cloud computing, and

high-definition film and recording businesses. Heat-assisted magnetic recording (HAMR) is the next leading technology

beyond current perpendicular magnetic recording (PMR) to meet the ever-increasing storage demand, as evidenced by

recent Seagate’s > 1.5Tbpsi spin stand basic technology demonstration and, more importantly, a working HAMR hard

drive with write-power-on-hour (WPOH) greater than 1000 hrs [1]. Among several material candidates for HAMR media,

chemically ordered-L10 FePt is the predominately investigated material due to its superior magnetic moment, low Curie

temperature and high magnetocrystalline anisotropy, enabling thermally stable small magnetic grains for high areal

density recording [2]. Though significant improvements have been achieved in microstructure, mechanical and thermal

design of the full HAMR media stack, tremendous challenges remain in every aspect to demonstrate HAMR a viable

technology for future magnetic recording technology.

What distinguishes HAMR from PMR in terms of recording is the working principle of HAMR that utilizes a laser to

elevate the media temperature during writing. With the introduction of an “effective thermal field”, the spatial gradient of

effective magnetic field is given by [3]:

(1)

where HW is the magnetic writing field of head and HK is the switching field of the media. The term “thermal gradient”

(dT/dx) depends on interaction between head and media during writing process.

Recent micromagnetic simulations indicate that jitter (the lower the number the higher the SNR) is strongly correlated

to Curie temperature distribution (Tc), grain size and thermal gradient of HAMR media as shown in Fig. 1 [4]. Combined

with low Tc, small well-defined grain size and right thermal

gradient, high areal density HAMR is achievable.

This presentation focuses on fundamental recording physics.

In addition, thermal gradient design and grain size reduction that

make FePt alloy an ideal choice for HAMR medium material are

discussed. Finally, challenges in the fabrication of FePt media

and how to implement them into a reliable HAMR hard drive

system will be covered.

1) C. Rhea et al., Seagate HAMR 1.6Tb/in2 Areal Density

Demonstration at Intermag 2016.

2) D. Weller et al.; Phys. Status Solidi A 210, p1245 (2013).

3) M. H. Kryder et al., Heat Assisted Magnetic Recording Proc.

IEEE, vol. 96, no. 11, pp. 1810–1835, Nov. 2008.

4) Pin-Wei Huang et al, Seagate internal communication 2016.

Fig. 1 Micromagnetic simulation shows the

correlation of jitter to Tc, thermal gradient and

gain size.

B-20

AC-04

Decomposable Cu3N layer for reducing L10 FePd ordering temperature

Ching Hung Hsiao, Chuenhou (Hao) Ouyang

Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan e-mail: houyang@mx.nthu.edu.tw

Cu3N/[Fe 3Å/Pd 4Å]5 thin films grown on Si/SiO2 substrates via dual ion beam sputtering system (Cu3N layer) and electron beam evaporation system (magnetic layer), and then treated with post annealing are investigated. It is known that Cu3N can thermal decompose into metallic Cu and nitrogen as temperature above 300 oC[1]. As treated proper thermal treatment, nitrogen can escape from thin film and vacancy will be generated. Therefore, this remaining vacancy could assist the intermixing of Fe and Pd, leading to promote L10 ordering at low temperature [2]. (100) preferred oriented Cu3N layer is realized with nitrogen bombard during preparation process at 100 oC and it will dissociated to (111) Cu phase as elevated to 250 oC, as shown in Fig. 1. [Fe 3Å/Pd 4Å]5 were grown on 1 nm Cu3N layer at room temperature, and treated post-annealing at 600 oC for 30s via rapid thermal annealing in high vacuum. The out-of-plane coercivity (Hc,) is about 230 Oe. As, the growth temperature of [Fe 3Å/Pd 4Å]5 raising to 200 oC and treated post annealing, Hc, is elevated. Further optimized experimental processing parameters, structural and magnetic analysis of Cu3N/[Fe 3Å/Pd 4Å]5 films through transmission electron microscope, X-ray diffraction (XRD) and superconducting quantum interference device will be discussed. [1] K. J. Kim, et al., Journal of Crystal Growth, 222, 767 (2001). [2] J. W. Liao, et al., Applied Physics Letters, 102, 062420 (2013). Fig. 1 XRD of Cu3N (25 nm) with nitrogen bombardment during preparation at (a) 100 oC and (b) 250 oC.

B-21

AC-05

Curie temperature measurement of FePt film by infrared reflectivity

Seong-Jae Jeon, Koichi Akahane, Shin Saito

Department of Electronic Engineering, Tohoku University, Sendai, Miyagi, Japan e-mail: jsjigst@ecei.tohoku.ac.jp

In recent years, heat-assisted magnetic recording is being actively studied for trilemma breaker in the hope that higher temperatures will assist magnetic reversal of small grain with high Ku at room temperature. And also a convenient and quick method for assessing Curie temperature (Tc) would be a key advance for developing materials that can be used effectively for thermally assisted recording. In this research, novel method to evaluate the critical temperature for change in the magnetic phase of FePt-C film has been reported by using optical properties especially in infrared wavelength region.

To determine Tc of media materials with granular structure, short range magnetic ordering should be distinguished from blocking phenomenon by thermal agitation because of small magnetic grains around Tc. Since the optical response of the conduction electrons is affected by the magnetic phase, measure of change in optical response can be effective way to evaluate Tc. Figure 1 shows the IR reflectivity measurement system. The system includes vacuum heating chamber and optical apparatus. IR light reflected from a FePt sample travels to the detector while elevating a temperature of the sample. Reflectivity profile against the temperature for the FePt film was measured as shown in Fig 2. The result clearly shows that the reflectivity changed around 513 oC. The temperature evaluated on this research is higher than reported value that was estimated by the variance of magnetization [1]. The reported temperature should be due to the blocking temperature which comes from thermal agitation. It is suggested that the distinct change in reflectivity results from the change in magnetic phase. [1] M. Wataneba et al., Mat. Trans. JIM, 37, 489 (1996).

Fig. 1 IR reflectivity measurement system

Fig. 2 Temperature dependence of

reflectivity for FePt-C film

B-22

AC-06

Reversible Hydrogenation Effect on Magnetism of Pd-related

magnetic thin films and nanostructures

Wen-Chin Lin(a),* and Yu-Chuan Chen(a)

(a)Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan

*Email: wclin@ntnu.edu.tw

Keywords: Magnetism, alloy, thin film, hydrogenation.

Pd has been widely used as a high efficient catalyst for hydrogen dissociation and

absorption. In our previous studies on Pd/Co/Pd or Co-Pd alloy thin films, the magnetic coercivity (HC) was reversible changed with the exposure to hydrogen. Besides, we deposited various Pd-related alloy thin films and nanostructures, such as Co-Pd alloy nanostructures on anodic aluminum oxide (AAO) and thin films on Al2O3(0001). The Co/Pd alloy deposit grown on the AAO template formed nano-dots, nano-pillars or anti-dots, depending on the deposited coverage. The size and distribution of the Co-Pd nanostructure were investigated by scanning electron microscope (SEM). The magnetic property was investigated by magneto optical Kerr effect (MOKE) in perpendicular and in-plane directions under different hydrogen atmosphere pressure. The exposure to hydrogen gas led considerable change of magnetic properties. The detailed mechanism of hydrogenation effects on magnetism are discussed in this report. These experimental observations are valuable for the combination of spintronic devices and catalyst materials. [Reference 1 W. C. Lin, B. Y. Wang, H. Y. Huang, C. J. Tsai, V. R. Mudinepalli

J. Alloys Comp. 661, 20-26 (2016). 2 W.C. Lin, C.J. Tsai, H.Y. Huang, B.Y. Wang, V.R. Mudinepalli, and H.C. Chiu

Appl. Phys. Lett. 106, 12404 (2015). 3 W. C. Lin, Cheng-Jui, Tsai, Xin-Ming Liu, and Adekunle O. Adeyeye

J. Appl. Phys. 116, 073904 (2014). 4 W. C. Lin, C.-J. Tsai, B.-Y. Wang, C.-H. Kao, and W.-F. Pong

Appl. Phys. Lett. 102, 252404 (2013).

5 C.-C. Chiu, W. C. Lin, Y.-C. Yeh, and K.-J. Song Appl. Phys. Lett. 102, 242403 (2013).

6 W. C. Lin, C.-S. Chi, T.-Y. Ho, C.-J. Tsai

Thin Solid Films, 531, 487 (2013).

B-23

AC-07

Study of the Interfacial interactions and the relevant Ferromagnetism of Ag/TiO2 core-shell nanoparticles

Yin-Ting Hsiao, Eric Nestor Tseng, Pin-Yu Chen, William Lee, Shih-Yun Chen*

Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan

This study reports a new concept for a nanomaterial in terms of both synthesis and

properties. The Ag@TiO2 core-shell nanoparticles were synthesized successfully via

two steps method. Ag nanoparticles (NPs) were first synthesized on TiO2 substrate by

thermal assisted photoreduction method (TAP) then TiO2 NPs were deposited on the

surface of Ag NPs by chemical reduction. No surfactants or organic compounds were

used during synthesis. X-ray absorption spectroscopy (XAS) and electron energy loss

spectroscopy (EELS) were utilized to study the interfacial interactions, including the

charge transfer between Ag and Ti and the induced oxygen related defect. Strain effect

and the distribution of oxygen defect were investigated by high resolution transmission

electron microscope (HRTEM). It is demonstrated that after introducing core-shell

structure, oxygen related defects were induced and concentrated within several layers

of TiO2 shell. In addition, the band structure of Ag core changed. Abovementioned

structural differences were then correlated to the observed ferromagnetism of Ag/TiO2.

This discovery provides a structure to induce and manipulate magnetic moments in

non-magnetic materials, which have potential applications in spintronics.

B-24

AC-08

Positive exchange bias in potassium split graphene nanoribbons

M. Venkat Narayana(a), Srinivasa Rao Singamaneni(b), and Suryanarayana

Jammalamadaka(a)

aMagnetic materials and device physics laboratory, Department of Physics, IIT

Hyderabad, Telangana-502285, India bMaterials Science Division, Army Research Office, Research Triangle Park, North

Carolina 27709, USA Corresponding author: ph13p0003@iith.ac.in, surya@iith.ac.in

We demonstrate on the effect of the negative cooling magnetic field on the exchange bias

properties of the graphene nanoribbons (GNRs). Upon the negative field cooling from 300 K to 5 K,

the hysteresis loop shifts along the negative magnetic field axis, which is same as the cooling field

direction. From the above observation we believe that there exists a positive exchange bias in GNRs.

Variation of the exchange bias with respect to the cooling field is found to follow a typical behavior

which is analogous to the phase separated manganites. In this manuscript we also demonstrate the

variation of exchange bias and the coercive field as a function of negative cooling field.

References: 1. S. S. Rao, S. Narayana Jammalamadaka, A. Stesmans, and V. V. Moshchalkov, J. van Tol, D.

V. Kosynkin, A. Higginbotham-Duque and J. M. Tour, Nano Lett., 12, (2012)1210–1217.

2. S. Narayana Jammalamadaka, S. S. Rao, J. Vanacken, V. V. Moshchalkov, Wei Lu and J. M. Tour, Appl. Phys. Lett. 101, (2012) 142402.

Fig. 1: Magnetization and positive

exchange bias effects in GNRs

B-25

BP-01

Magnetic random access memory (MRAM) has got intensive attention during these years.

For spin-orbit-torque (SOT) MRAM, it possess lower write current compared to spin-transfer-torque (STT) MRAM[1] , which improves the energy efficiency and the scalability in logic circuit[2,3] . The spin-orbit-torque arises mainly from two difference sources, one is the spin current generated by bulk spin Hall effect(SHE), the other one is the effective magnetic field due to the heterostructure interfaces. With the basic structure composed of a ferromagnet (FM) layer and a adjacent heavy mental layer, when the in-plane current flowing into the structure will generate the pure spin current perpendicular to the film acting on the magtization of FM. Generally, we need an additional external in-plane magnetic field to allow the deterministic switching in FM which has perpendicular magnetic anisotropy (PMA)[2]. Despite this in-plane field may be integrated into the devices by back-end process, like package. There has some solution been proposed by introducing the lateral asymmetry in oxide layer[4] . Based on this method, we know build-in a magnetic field or giving another forces may be a way to solve the unwanted external field for engineering. Therefore we use an antiferromagnet (AFM) adjacent the FM layer to give the in-plane force by the exchange-bias. In this work, we prepared stacks consisting of Pt/Co as heavy mental layer an FM layer separately and then with varied IrMn thickness on the top of it (Fig1). After annealing at 200oC for 30 minutes, the present of PMA and in-plane bias- field was verified by the vibrating sample magnetometer (VSM). To study the SOT switching behavior, the magnetization was measured by focused polar magneto-optical effect (FMOKE) after each electric pulse. Surprisingly, the magnetization of FM fully switched when the pulse reached the critical current density without any external magnetic field (Fig.2).

Reference [1]Liu, L., et al. Phys Rev Lett 109, 096602, (2012). [2]Liu, L., et al. Science 336, 555-558 (2012). [3]Ralph, D. C. and M. D. Stiles (2008). Journal of Magnetism and Magnetic Materials 320, 1190 (2008). [4]Yu, G., et al. Nat Nanotechnol 9, 548-554 (2014)

Field-free magnetization switching by current-induced torque with antiferromagnetic/ferromagnetic structure

Ming-Han Tsai, Kuo-Feng Huang, Ding-Shuo Wang, and Chih-Huang Lai

Department of Material Science Engineering, National Tsing Hua University, Hsinchu, 300,

Taiwan email : hank892004@hotmail.com.tw

Fig.1 Schematic structure

cross section

Fig.2 Magnetization versus current

density loop at zero field

B-26

BP-02

Thermal stability of CoFeB-MgO free layer with

perpendicular anisotropy in different size of devices Hung-Yi Tsai, Chun-Liang Yang , Chih-Huang Lai

Department of Materials Science and Engineering, National Tsing Hua University,

Hsinchu, Taiwan e-mail: tsai8234209@hotmail.com

Spin-transfer-torque magnetic random access memories (STT-MRAMS) are

attracting much attention because of their potential in offering reduction of power

consumption through non-volatility and reduction of the size of memory cells. Now a

days, many groups study MTJs with perpendicular magnetic easy axis because of the

advantages in switching current and thermal stability. There are different kinds of

material with perpendicular easy axis as ferromagnetic electrodes in MTJs. Among

them, CoFeB-MgO was shown to have high potential to satisfy major requirements for

integration of MTJs with complementary metal-oxide-semiconductor[1][2].

We have investigated thermal stability of the perpendicular CoFeB-MgO as free

layer in micron and nano size by methods of dynamic coercivity and pulse magnetic

switching probability. We have verified the relationship between thermal stability and

Keff*t which can be measured in sheet film. Moreover, we successfully deposit a

double CoFeB free layer with higher thermal stability.

[1]H.Sato et al,APPLIED PHYSICS LETTERS 101, 022414 (2012)

[2]V.B Naik et al, AIP ADVANCES 2, 042182 (2012)

-250 0 250

0.0

0.2

0.4

0.6

0.8

1.0

No

rmal

ized

Hal

l Vo

ltag

e

H(Oe)

0.0 110 120 130 140 150 160 170 1800.0

0.2

0.4

0.6

0.8

1.0

Sw

itch

ing

pro

bab

ility

Pulse magnetic field(Oe)

Fig.1 SEM image of device

(size 100nm) Fig.2 VH loop(out of plane)

of device(size 100nm)

Δ~52

Fig.3 The result of pulse

magnetic switching

probability method

B-27

BP-03

a.

b. b. 0

a.

Spin-orbital torque induced by Baron impurities in Platinum Bo-yuan Yang, and Chih-Huang Lai

Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan.

To achieve good PMA and high tunnel magnetoresistance ratio (TMR), a

annealing procedure is used to crystalize amorphous CoFeB [1]. However, this annealing process may also cause interdiffusion between layers. Recently, our group found that the baron (B) diffuse from CoFeB to adjacent Pd layer may induce large spin orbital torque which significantly increases the spin hall angle. In this work, the Ti(5nm)/Pt(B doped, 5nm)/ /Ti(5nm) structures was prepared, and we directly doped B into Pt layer by co-sputtering. The doping concentration can be adjusted by changing the RF sputtering power of B. The 1st harmonic hall voltage and 2nd harmonic hall voltage are acquired by the lock-in measurement to evaluate the effective magnetic field induced by spin orbital torque [2]. Fig.1a shows that there is no strong relation between the B concentration and the effective field before applying post-annealing to the samples. On the other hand, after the samples annealed at 200°C for 10 min, the B doped samples show increments in effective magnetic field (Fig.1b). In particular, there is a significant increase in longitudinal effective field for 15 watts power doped device (triangle) which is about 20% larger than that of the undoped sample (square). The transverse effective fields only show limited change after annealing (Fig.2). These results implied that B impurities may induce damping-like torque which increases longitudinal SOT efficiency.

[1] Y.M. Lee, J. Hayakawa, S. Ikeda, F. Matsukura, and H. Ohno, Applied Physics Letters 89, 042506 (2006). [2] J. Kim, J. Sinha, M. Hayashi, M. Yamanouchi, S. Fukami, and H. Ohno, Nature Materials 12, 240 (2012).

Fig.1 Fig.2

B-28

BP-04

Effects of interfacial exchange interaction on the antiferromagnet-induced perpendicular magnetic

anisotropy

M. S. Tsai(a),P. H. Lin(a),C. W. Shih(a),M.J. Lee(a),C. W. Huang(a), N. Y.Jih(b), D. H. Wei(c), and B. Y. Wang(a),*

(a)Department of Physics, National Changhua University of Education, Changhua 500 Taiwan

(b)The Center of Teacher Education, National Chung Hsing University, Taichung 402, Taiwan

(c)National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan *Email: bywang1735@cc.ncue.edu.tw

Antiferromagnetic (AFM) layers have been known to exert many effectson adjacent ferromagnetic (FM) layers, including coercivity enhancement, exchange bias, and magnetization switching.Several studies have suggested the magnetization reorientation can be induced by the uncompensated moment of the AFM layer at the AFM/FM interface [1]. Nevertheless, the effect of interfacial AFM moments on the induced PMA of adjacent FM layer is not fully clear.Here, we report an experimental investigation onthe effects of interfacial coupling of the AFM films on the induced perpendicular magnetic anisotropy (PMA) in epitaxially grown Mn/2 ML Co/14 ML Ni films. Magnetic hysteresis loops show that the PMA is established when monolayer Mn film was deposited. Further increasing the Mn layer thickness (tMn)leads to presence of in-plane magnetic anisotropy. The PMA is established again while tMn is large than 6 ML (Fig 1(a)). Meanwhile, the structure of Mn is changed from c-fct to e-fct. Moreover, we also vary the interface properties by using Mn-based alloy AFM films. A significant change on the behavior of induced PMA is observed.According to these results, we indicate that antiferromagnet-induced PMA is highly sensitive to the interfacial moments of the AFM films and the magnetic interaction of such moments with the volume moment.

[1]B. Y. Wang et al., Phys. Rev. B 92, 214435 (2015). Fig. 1. (a)Average interlayer distance (d ⊥ ) of

various Mnfilms calculated according to the energy

peaks (I) in the I/V curves atRT or 150 K (LT).

Thed⊥of the Mn films changed from approximately

1.71 to 1.88 Å when tMn> 6 ML. (b) Magnetic

hysteresis loops of 0-14 ML Mn/2 Mn Co/14 ML

Ni/Cu(001) films.

B-29

BP-05

Magnetic proximity effects

on antiferromagnet-induced perpendicular magnetic

anisotropy in Ni/Co/Mn/Co/Cu(100) films C. W. Huang(a), M. S. Tsai(a), P. H. Lin(a), D. H. Wei(b), and B. Y. Wang(a)*

(a)Department of Physics, National Changhua University of Education, Changhua

500, Taiwan (b) National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan

*e-mail: bywang1735@cc.ncue.edu.tw

It has been reported that the magnetic proximity effects between adjacent

magnetic layers could enhance the magnetic ordering of the film with the lower

magnetic ordering temperature [1]. In this study, 12 ML Ni/1-2 ML Co/4 ML Mn/1-5

ML Co/Cu(100) ultrathin films were prepared for studying the magnetic proximity

effects on the antiferromagnet-induced perpendicular magnetic anisotropy (PMA). The

growth and crystalline structure of films were monitored by medium energy electron

diffraction (MEED) and low-energy electron diffraction (LEED), respectively. The

results of magneto-optical Kerr effect show that the PMA of top Ni/Co films is

enhanced by increasing the thickness of the bottom Co film. Since the in-plane

magnetic anisotropy of the bottom Co film is known to be enhanced with the film

thickness, the promoted PMA of top Ni/Co film is unlikely to be induced by the

long-range exchange coupling from the bottom Co film, but could be attributed to the

enhanced antiferromagnetic ordering of the Mn film through magnetic proximity

effects.

[1] B. Y. Wang, C. C.Chui, W. C. Lin, and M. T. Lin, Appl. Phys. Lett. 103, 042407

(2013). Fig. 1(a) Interlayer distance of various Ni or Mn films measured by LEED I/V. (b) Magnetic hysteresis loops of 12 ML Ni/1 ML Co/4 ML Mn/1-5 ML Co /Cu (100) films. The magnetic proximity effects on antiferromagnet-induced PMA are indicated by top illustrations.

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BP-06

Perpendicular magnetization of FeCo thin film deposited on Cu (001)

by alternate monatomic layer deposition

(a)J. Ochiai, (a)M. Tomita, (b)T. Ohkochi, (c)T. Miyamachi, (c)F. Komori,(a)M. Kotsugi

(a)Tokyo University of Science, Tokyo 125-8585, Japan

(b)SPring-8/JASRI, Hyogo 679-5198, Japan

(c)ISSP, Chiba 277-0882, Japan

e-mail : canata1130@gmail.com.

Act against global warming, development of advanced magnetic material has been

rapidly progressed in this decade. L10-type FeCo order alloy is a candidate of such

advanced magnetic material. Its predicted magnetic anisotropy energy is 1×108 erg/cc

and magnetic moment is 1800 emu/cc [1]. Here, We examine magnetic property of

FeCo thin films fabricated by pulsed-laser-deposition method. Magnetization curves

show saturation magnetization (Ms) of 265 emu/cc, out-of-plane magnetization is

greater than in-plane magnetization therefore, easy axis of magnetization is

out-of-plane (Fig.1). Magnetic domain structure shows maze-pattern (Fig.2). From

these results it can be concluded that FeCo film obtains perpendicular magnetization

with spontaneous magnetization.

Fig.1 Magnetization curves with magnetic

fields parallel (In-plane) and perpendicular

(Out-of-plane) to the film plane

Ref)

[1] T.Burkert,et al.,PRL.93,027203,(2004).

Fig.2 Magnetic domain structure

shows maze-pattern at initial

magnetization state

B-31

BP-07

FePt(200)+(002)

(b-2)

(a-2)

(c-2)

MgO(200)

WL

K

FePt(001)

20 30 40 502 (deg.)

FePt(200)+(002)+(020)

(c-1)

(b-1)

(a-1)

MgO(002)

WL

K

FePt(001)

30 40 50202 (deg.)

Inte

nsit

y (a

rb. u

nit)

In-planeOut-of-plane

100 nm

40 nm

10nm

FePt(200)+(002)

(b-2)

(a-2)

(c-2)

MgO(200)

WL

K

FePt(001)

20 30 40 502 (deg.)

FePt(200)+(002)+(020)

(c-1)

(b-1)

(a-1)

MgO(002)

WL

K

FePt(001)

30 40 50202 (deg.)

Inte

nsit

y (a

rb. u

nit)

In-planeOut-of-plane

100 nm

40 nm

10nm

Fig. 1 (a-1)–(c-1) out-of-plane and (a-2)–(c-2) in-plane XRD patterns of FePt epitaxial films of (a) 10, (b) 40, and (c) 100 nm thicknesses.

Mag

neti

zati

on (

emu/

cm3 )

Applied magnetic field (kOe)

(b) 40 nm

–10 0 5– 5 10–10 0 5– 5 10

1000

–1000

0

(a) 10 nm

⊥

//⊥

//

Mag

neti

zati

on (

emu/

cm3 )

Applied magnetic field (kOe)

(b) 40 nm

–10 0 5– 5 10–10 0 5– 5 10

1000

–1000

0

(a) 10 nm

⊥

//⊥

//

Fig. 2 Magnetization curves measured for FePt epitaxial films of (a) 10 and (b) 40 nm thicknesses.

Influence of Film Thickness on the Structure and Magnetic Properties

of FePt and CoPt Films Formed on MgO(001) Substrate

Masahiro Nakamura(a), Ryoma Ochiai(a), Mitsuru Ohtake(a,b), Masaaki Futamoto(a), Fumiyoshi Kirino(c), and Nobuyuki Inaba(d)

(a)Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan (b)Faculty of Engineering, Kogakuin University, Tokyo 192-0015, Japan

(c)Graduate School of Fine Arts, Tokyo University of the Arts, Tokyo 110-8714, Japan (d)Faculty of Engineering, Yamagata University, Yamagata 992-8510, Japan

e-mail: m-nakamura@futamoto.elect.chuo-u.ac.jp FePt and CoPt alloy thin films with L10 structure have been investigated for recording

media, MRAM devices, etc. For such applications, control of the easy magnetization axis (c-axis) perpendicular to the film plane is required in addition to realization of high order degree and flat film surface. The film lattice strain caused by a lattice mismatch with the substrate plays an important role in aligning the c-axis of L10 crystal, and a lateral expansion is considered to enhance the ordering with the c-axis normal to the substrate [1].However, the strain in magnetic film decreases with increasing the distance from the substrate. In the present study, FePt and CoPt films with different thicknesses (10 - 100 nm) are prepared by employing a two-step method consisting of deposition at 200 °C followed by annealing at 600 °C. The structure and the magnetic properties are investigated.

Fig. 1 shows the out-of-plane and in-plane XRD patterns measured for FePt films. L10(001) superlattice reflections are observed both in the out-of-plane and the in-plane XRDs, which indicates that the films include L10(100) variants with the c-axis lying parallel to the substrate surface together with L10(001) variants with the c-axis perpendicular. The decrease of L10(001) intensity with reducing the thickness observed in the in-plane XRDs indicates that the L10(100) variant volume ratio is decreasing for thinner films. Fig. 2 shows the M-H curves. The 10-nm-thick film shows strong perpendicular magnetic anisotropy, whereas the 40-nm-thick film shows in-plane anisotropy. The magnetic anisotropy is reflecting the L10-variant structure in FePt film. The results of CoPt films will be presented at the conference. [1] M. Ohtake et al.: IEEE Trans. Magn., 50, 2104204 (2014).

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BP-08

Improvement in the resistive switching properties and

magnetic

of Ag/HfO2/p-type Si film device by doping cobalt

Shin Ru Chiou* , Yu Min Hu and Huang Wei Chang Department of Applied Physics, National University of Kaohsiung 81148, Taiwan,

R.O.C.

E-mail address: jackymo208@hotmail.com

Abstract

In the past decade, binary transition metal oxides have been extensively

investigated as the key materials for both spintronic and resistive random access

memory (RRAM) devices. Among them, hafnium dioxide (HfO2) has attracted much

attention due to its excellent resistive switching (RS) properties as well as

ferromagnetism with/without ferromagnetic dopants. In this work, we studied the

effect of cobalt (Co) dopant on the RS properties of HfO2 film. A

metal/insulator/semiconductor (MIS) configuration of HfO2 film device was deposited

by using a magnetron sputtering method on p-type conducting silicon substrate at 500 and capping a thin Ag layer as the top electrode. For comparison, we also prepared

the Ag/Co-doped HfO2/p-type Si film device. From the I-V measurements, we

observed excellent and stable bipolar RS properties in both MIS samples. For the HfO2

MIS sample, the set/reset voltages and high/low resistance ratio are 3.77/-3.18 V and

106. For the Co-doped HfO2 MIS sample the set/reset voltages and high/low resistance

ratio are 8.52/-3.11 V and 105. But The stability of RS of Co-doped HfO2 sample is

better than that of HfO2 MIS sample. According to M-H curves the Co-doped HfO2 in

high/low resistance states exhibited different saturation magnetizations. The results

suggest that the Co dopant may improve the RS properties and magnetism.

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BP-09

Garnet films fabricated by metal organic decomposition method on glass substrates and Gd3Ga5O12 substrates

Hina Saito(a), Yoshito Ashizawa(b), and Katsuji Nakagawa(b)

(a)Graduate School of Science and Technology, Nihon University, Chiba, Japan

(b)College of Science and Technology, Nihon University, Chiba, Japan e-mail: saito_hina@inl.ecs.cst.nihon-u.ac.jp

Garnet films are very useful magnetic films for magnon devices as well as spin Seebeck devices. We fabricated Y3Fe5O12 (YIG), (YBiR)3(FeGa)5O12 (R = Dy, Eu, Gd) on Gd3Ga5O12 (GGG) and glass substrates (Corning: Eagle-XG) by the Metal Organic Decomposition (MOD) method. Dy, Eu, and Gd were chosen to control magnetostriction of garnet films, respectively.

MOD solusions for garnet films were spin-coated on substates, then dried at 100 °C for 10 minutes, and then decomposed and volatelized at 450 °C for 10 minutes. The thickness of a single-coated garnet films were expected to be 40 nm [1]. We repeated this process 4 times. After the process, the films were annealed to be crystalized at various temperatures higher than 750 °C.

We studied uniaxial magnetic anisotorpy and estimated magnetostriction constant for the films fabricated by the MOD method, even though there are many studies for garnet films fabricated by the Liquid Phase Epitaxy (LPE) method [2].

Depending on magnetostriction constant, the uniaxial magnetic anisotorpy of the film changes. One of the films, for example, shows that easy axis of magnetization of the film is perpendicular to the plane because of Gd substitution, as shown in Fig. 1.

The uniaxial magnetic anisotorpy constant Ku of the films on glass substrates measured by torque magnetometer, and their magneto-striction constant λs derived by Ku are shown in Table 1. The λs is changed depending on substitution of rare earth elements for c site.

Acknowledgements

This work is partially supported by a Grant of MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2013-2017.

[1] T. Ishibashi, A. Mizusawa, N. Togashi, T. Mogi,

M. Houchido, K. Sito: J. Crystal Growth, 275, e2427-e2431 (2005).

[2] K. Matsuumi: Magnetic bubbles, edited by S. Iida and H. Kobayashi (Maruzen, Japan, 1977), pp.84-92. [in Japanese]

Fig. 1 Faraday hysteresis loop of Y1.5Bi1Gd0.5Fe4Ga1O12 on GGG substrate at room temperature.

Table 1 Uniaxial magnetic anisotropy constant Ku and magnetostriction constant λs of Y1.5Bi1R0.5Fe4Ga1O12 films (R = Dy, Eu, Gd) on glass substrates.

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BP-10

Study of a 4.5-T Wavelength Shifter Prototype with a Cryogenic PrFeB Permanent Magnet

Chao-Chin Wang(a) (b), Cheng-Hsiang Chang (b), Hui-Huang Chen(b) Ching-Shiang Hwang(b), Chih-Hao Lee(a)

(a)Department of Engineering and System Science, National Tsing Hua University,

Hsinchu, Taiwan (b)National Synchrotron Radiation Research Center, Hsinchu, Taiwan

e-mail: chang@nsrrc.org.tw

A wavelength shifter is a high-field insertion device to extend the critical photon energy in a synchrotron light source. It is composed of one high-field central pole and two compensating poles. In this work, a 4.5-T high-field cryogenic wavelength shifter (CWLS) for Taiwan Photon Source (TPS, 3-GeV ring) has been studied. CWLS consists of a cryogenic PrFeB permanent magnet at 77 K and vanadium permendur pole. The overall dimensions of the magnet array are height 205 mm, length 240 mm, width 120 mm, and operation in a 5-mm gap. The residual flux density of PrFeB at 77 K and the saturation of vanadium permendur are 1.67 T and 2.4 T, respectively. The longitudinal section view of CWLS is shown in fig.1, in which the bold arrows denote the magnetization direction of the permanent magnets. The strong intrinsic coercivity (HCJ = 6200 kA / m) of PrFeB at 77 K can avoid the permanent magnets becoming irreversibly demagnetized. The simulation result with TOSCA (Opera-3d) shows that the maximum field magnitude B0 can attain 4.54 T at 77 K (fig. 2). The two compensating poles have been optimized to meet the tolerance requirement of the integral multipole field error for TPS. This 4.5-T wavelength shifter can shift the critical photon energy from 7.1 keV to 27 keV, which provides broad hard X-rays for experiments requiring high photon energies. The construction of CWLS prototype and the measurement of the magnetic field are discussed in this work.

Fig. 1 Longitudinal section view

of the wavelength shifter.

Longitudinal Position (cm)

-30 -20 -10 0 10 20 30

Ver

tica

l Fie

ld (

T)

-4

-2

0

2

4

B0 = 4.54 T

Fig. 2 Vertical field as a function of the

longitudinal position.

B-35

BP-11

Magnetically driven dynamics of bio-functionalized beads via on-chip micromagnets

Xinghao Hu, Byeonghwa Lim, Sandhya Rani Goudu, Eunjoo Jeong, Sri Ramulu Torati, CheolGi Kim

Department of Emerging Materials Science, DGIST, Daegu, 711-873, Republic of

Korea. e-mail: xinghao@dgist.ac.kr

We investigate the non-linear dynamics of bio-functionalized beads moving around

the periphery of patterned magnetic disks in the presence of an in-plane rotating magnetic field. Three different dynamical regimes are observed in experiments [1], including (1) phase-locked motion at low driving frequencies, (2) phase-slipping motion above a first critical frequency fc1, and (3) phase-insulated motion above a second critical frequency fc2. Experiments with Janus particles were used to confirm that the beads move by sliding rather than rolling. The rest of the experiments were conducted on spherical, isotropic magnetic beads, in which automated particle position tracking algorithms were used to analyze the bead dynamics. Experimental results in the phase-locked and phase-slipping regimes correlate well with magnetic force simulations [2]. Additional assumptions are required to predict the onset of the phase-insulated regime, in which the beads are trapped in closed orbits; however, the origin of the phase-insulated state appears to result from local magnetization defects. These results can find use in the development of new systems for separating magnetic beads and cells on-chip in high resolution. For example, using our half-disk pathway [3] different kinds of magnetic beads and cells in the magnetization or scale could be separated due to the different critical frequencies of the non-linear dynamics. Furthermore, an innovative approach based on bead dynamic factors can be implemented to quantify the frictional and viscous properties of nano-bio-interfaces for the precise control of bio-functionalized beads in microfluidic channels, and also for understanding the biological interaction in surface science. [1] X. Hu, R. A. Nassab, B. Lim, Y. Yang, M. Howdyshell, R. Sooryakumar, B. B. Yellen, and C. G. Kim, J. Appl. Phys., 118, 203904 (2015). [2] X. Hu, B. Lim, I. Jeong, A. Sandhu, and C. G. Kim, IEEE Trans. Magn., 49, 408 (2013). [3] B. Lim, V. Reddy, X. Hu, K. Kim, M. Jadhav, R. A. Nassab, Y. W. Noh, Y. T. Lim, B. B. Yellen, and C. G. Kim, Nature Commun., 5, 3846 (2014).

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BP-12

Detection of magnetic circular dichroism in amorphous materials

utilizing a single-crystalline overlayer P. L. Ho(a), J. Lin(a), X. Y. Zhong(a), C. Song(b), J. Rusz(c), H. L. Xin(d), B.

Cui(b), V. Kocevski(c,e), L. L. Han(d), R. Q. Lin(d) and J. Zhu(a)

(a)National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and

Engineering, Tsinghua University, Beijing 100084, China.(b)Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084,

China.(c)Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala S-75120, Sweden.(d)Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.(e)Department of Materials Science and Engineering, Northwestern University, Evanston,

Illinois 60208, USA.

E-mail:hbl15@mails.tsinghua.edu.cn

As the technology of high-spatial resolution electron energy loss spectroscopy, an electron magnetic chiral dichroism (EMCD) method was regarded as a quantitative method of measuring spin and orbital magnetic moments, which is equivalent to x-ray magnetic circular dichroism (XMCD). Using the analytical method of EMCD in a transmission electron microscope allows the quantification of the magnetic structure of crystalline materials down to the nanometer scale [1-3]. However, the restricting by the confined diffraction geometry applied in experiments [4], none experiments or theories have been performed to obtain the EMCD signals for amorphous materials yet, due to the lack of long range ordering. In this work, we demonstrate it is possible to detect element-specific magnetic signals in amorphous materials utilizing a single-crystalline overlayer as an EMCD beam splitter for the first time. The approach is applied to a bilayer sample where a enough thin amorphous magnetic FeOx layer that is grown on a single-crystalline Y2O3 stabilized ZrO2 substrate. We found the results for both experimental evidences and theoretical calculations lead to unprecedented EMCD signals. The quantitative orbital to spin magnetic moment ratio of Fe in amorphous FeOx layer has been achieved. Our approach allows us to break through the constraint of crystal formats in the EMCD spectra measurements, providing new prospects of detecting EMCD signals from amorphous and ultrathin materials at the nanometer scale. This approach might also be extended to the magnetic quantitative analysis of other heterogeneous materials at high spatial resolution. This work may open a door to meet the challenge of exploring magnetic states and behaviors of amorphous films, and have important consequences for revealing the magnetic structures of magnetic materials in various crystal forms using transmission electron microscopy at the nanoscale. [1] Schattschneider, P., et al, Nature 441, 486 (2006). [2] Rusz, J., et al, Phys. Rev. B 75, 214425 (2007). [3] Wang, Z.Q., Zhong, X. Y., et al, Nat. Commun. 4, 1395 (2013). [4] Lidbaum, H., et al, Phys. Rev. Lett. 102, 037201 (2009).

Acknowledgements: This work was financially supported by National 973 Project of China (2015CB921700, 2015CB654902), National Natural Science Foundation of China (51471096, 11374174, 51390471 and 51322101), Tsinghua University Initiative Scientific Research Program and National High Technology Research and Development Program of China (2014AA032904). This work made use of the resources of the National Center for Electron Microscopy in Beijing and Tsinghua National Laboratory for Information Science and Technology. J.R. acknowledges financial support of Swedish Research Council, STINT and Göran Gustafsson's Foundation. H.L. Xin. acknowledges support from the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.

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BP-13

Carrier role of superparamagnetic particles and beads in digital magnetophoretic circuits for living cell control

Sandhya Rani Goudu, Byeonghwa Lim, Xinghao Hu, CheolGi Kim

DGIST, Korea

We demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single superparamagnetic beads and magnetic-nanoparticle-labelled single cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, capacitors and diodes of electronic circuits. The current lines are used to establish active circuitry for switching particles and cells between different tracks similar to gated electrical transistors. When combined into arrays, these integrated circuits have general multiplexing properties and thereby paving the way for the development of digital circuitry for the precise control of magnetizable objects. Magnetic-micro sized beads and magnetic-nanoparticle-labelled single cells can be reasonably approximated as magnetic point dipoles if they are exposed to weakly inhomogeneous magnetic field distributions on the length scale of the particle. In such cases, the magnetic objects are moved towards the nearest locations of the instantaneous minima of the magneto-static potential energy that occurs where the local substrate field is parallel to the external field. By shifting the energy minima across the substrate in a programmable manner, the trajectory of single particles can be precisely controlled. If the magnetic field distribution is modulated in time at a sufficiently slow rate, a simple model can demonstrate the similarity between current of magnetic particles and Ohm’s law for electrical circuits, thereby providing motivation for pursuing more complex circuit analogies.

Fig: Cell chip arrays

References:1. Magnetophoretic circuits for digital control

of single particles and cells. Nat. Communication 5, 3846 (2014).

2. Dominguez, M. H. et al. Highly multiplexed quantitation of gene expression on single cells. J. Immunol. Methods 391, 133–145 (2013).

3. Yin, H. B. & Marshall, D. Microfluidics for single cell analysis. Curr. Opin. Biotechnol. 23, 110–119 (2012).

B-38

PA-01

Cell manipulation using magnetic honeycomb structure

Chen-Yu Huang,(a) Yong-De Xu,(b) Ching-Ming Lee,(b) Te-Ho Wu,(b) Ming-Shinn Hsu,(c)* Zung-Hang Wei(a)*

(a) Department of Power Mechanical Engineering, National Tsing Hua University,

Hsinchu City, Taiwan (b) Graduate School of Materials Science, National Yunlin University of Science and

Technology, Yunlin, Taiwan (c) Department of Obstetrics and Gynecology, Ching-Kuo Campus of Min-Sheng

Hospital, Taoyuan, Taiwan *e-mail: mingshsu@gmail.com; wei@pme.nthu.edu.tw

Cell manipulation techniques have aroused considerable attention in the field of biomedical research. A conceptual idea for cell manipulation that proposed by Carter et al. as early as 1965, [1] cell patterning technology, make use of unique features to control cell distribution, influence cell morphology as well as modulate cell function. Therefore, honeycomb-shaped magnetic thin films with domain wall (DW) pinning geometry are designed to actively trap magnetically labeled cells. After an initial in-plane magnetic field (Hinitial) is applied and later reduced to zero, the resultant magnetization became locally aligned. Human hepatocellular liver carcinoma cell line (HepG2) stably expressed green fluorescent protein (GFP) are magnetically labeled with superparamagnetic magnetic nanoparticles (MNPs). Prussian blue stain and single cell magnetophoresis are performed to evaluate the internalization of the MNPs. Magnetically labeled cells are then be trapped by the stray fields of head-to-tail DWs (HH DWs) or tail-to-tail DWs (TT DWs) (Fig.1). After co-culture with magnetic structure, HepG2 cells stretched out and showed filopodia-like protrusions and contacted with adjacent cells.

Fig. 1 (a) Illustration of magnetization configuration and local magnetic stray field distribution (b) coffee ring structure formed by magnetic nanoparticles attracted by the stray fields generated by DWs (c) Optical images and (d) fluorescence image of GFP-expressed HepG2 cells attracted and arranged at the vertices of the magnetized honeycomb structure.

[1] S. B. Carter, Nature, 208, 1183 (1965).

B-39

PA-02

CPP-GMR effects of Co2Fe0.4Mn0.6Si/L12-Ag-Mg/Co2Fe0.4Mn0.6Si devices:

Spacer layer thickness dependence

Yusuke Ina*, Takahide Kubota**, and Koki Takanashi

IMR, Tohoku Univ.

e-mail: *ina@imr.tohoku.ac.jp, **tkubota@imr.tohoku.ac.jp

Introduction: Current perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices are promising for the application to reading heads of hard disk drives (HDDs) in future, which require a low resistance-area product (RA) and a high magnetoresistance (MR) ratio [1]. In a previous paper we reported the CPP-GMR devices with aRA value of 17 mm2 using a partially L12-ordered Ag83Mg17 spacer layer and Co2Fe0.4Mn0.6Si (CFMS) electrodes, which was larger than that of the conventional devices with a Ag spacer layer [2]. In this work, we prepared the CFMS/Ag-Mg/CFMS devices with a more ordered L12 Ag78Mg22 spacer layer and investigated the spacer layer thickness dependence of CPP-GMR effects. Experimental: A stacking structure of the samples was; MgO (100) sub./Cr (20 nm)/Ag (40 nm)/CFMS (20 nm)/Ag78Mg22 (t nm)/CFMS (7 nm)/Ag (2 nm)/Au (5 nm). All layers were deposited at ambient temperature, and in situ post-annealing was performed at 650ºC and 500ºC, after the depositions of Cr and the upper CFMS layers, respectively. The thicknesses of the Ag78Mg22 spacer layer, t, were 2, 3, and 5 nm. The crystal structure was investigated by using reflection high energy electron diffraction (RHEED) technique at the surface of the top CFMS layer. MR measurements were performed by direct current four-terminal method at room temperature. Results: As a result of RHEED observation, the epitaxial growth and the L21-ordering of the top CFMS layer were confirmed regardless of the spacer layer thickness. RA values of the CPP-devices were determined from the plots of the junction resistances at the parallel magnetization configuration (Rp) as a function of the inverse junction area (1/A). RA values and MR ratios increased with the spacer layer thickness. The values of MR ratio were 41%, 53% and 56% for t = 2, 3 and 5 nm, respectively. The maximum RA value was 20 mm2 for the samples with a 5 nm thick spacer layer. CPP-GMR effects of the devices with larger thicknesses will be discussed in the presentation. Acknowledgements: This work was supported by ImPACT program of the Council for Science, Technology and Innovation, and a KAKENHI (No. 25220910) from JSPS. References: [1] M. Takagishi, et al., IEEE Trans. Magn. 46, 2086 (2010). [2] H. Narisawa, et al., Appl. Phys. Express 8, 063008 (2015).

B-40

PA-03

Magnetic properties of microfabricated MnxGa circler dot arrays

H. Makuta, Y. Takahashi, R. Sato, T. Shima, and M. Doi

Department of Electronic Engineering, Tohoku Gakuin University, Tagajo 985-8537, Japan

e-mail: s1594352@g.tohoku-gakuin.ac.jp

Mn-Ga alloy attracts much attention as a new material for the spintronics device and the high-density magnetic storage media because of its high uniaxial crystalline magnet anisotropy (~ 107 erg/cm3)[1]. A lot of studies of Mn-Ga thin films have been performed [2], however, there are few reports about the Mn-Ga thin film in submicron size. In this study, MnxGa circular dot arrays have been microfabricated and a relation between the magnetic properties and the diameter of the dots have been investigated in order to obtain the design guide line of new high-performance magnetic thin film material for high-density magnetic recording. The MnxGa thin films ware prepared by an electron beam deposition system with MnxGa bulk deposition materials synthesized by the arc melting. A Cr buffer layer (5 nm) and a MnxGa layer (10 ~ 20 nm) were stacked on a single crystal MgO (100) substrate, finally, a Cr capping layer was deposited. The MnxGa circular dots were microfabricated from the continuous films through an electron beam lithography and an Ar ion milling. Diameter of the dots D was varied from 100 nm to 3000 nm. The composition of the deposition materials and the thin films was identified by an energy dispersive X-ray spectrometer (EDX). Surface of the substrate, the buffer, and the MnxGa layers was monitored by a reflection high energy electron diffraction (RHEED) in situ observation. Crystalline structure of the films was characterized by an X-ray diffraction (XRD). Magnetic properties of the films and the dots were characterized by a super conducting quantum interference devise magnetometer (SQUID) and a poler magneto optical Kerr effect (µ-MOKE) with the maximum magnetic field of ±70 kOe and ±20 kOe, respectively. From XRD pattern for the Mn1.0Ga thin film deposited at 300 ºC and annealed at 500 ºC, (001) superlattice peak and (002) fundamental peak were observed, indicating that the L10 ordered structure was formed. For the Mn1.5Ga and the Mn3.2Ga, the peaks from the L10 or D022 structure were not confirmed. Ms = 170 emu/ cm3 and Hc = 10.5 kOe was observed from magnetization curve for the Mn1.0Ga thin film with out-of-plane applied field. After the microfabrication of Mn1.0Ga continuous film, Hc = 14.6 kOe was observed in the dots with D = 3000 nm. Hc of the dots showed increase tendency with decrease of D. The relation between magnetic properties and the diameter of the MnxGa dots will be discussed in detail.

[1] S. Mizukami, et al., Phys. Rev. B 85, 014416 (2012). [2] E. Lu, et al., Phys. Rev. Lett. 97, 146101 (2006).

B-41

PA-04

Effect of microfabrication on the magnetic properties for Nd-Fe-B thin films with several cap layers

A. Sugawara, H. Iwama, R. Kurosu, M. Doi, T. Shima

Faculty of Engineering, Tohoku Gakuin University, Tagajo, Japan e-mail: s1594331@g.tohoku-gakuin.ac.jp

Nd-Fe-B sintered magnets have been widely used in many applications such as motors, actuators and sensors, since they possess highest maximum energy products (BH)max among all permanent magnets. However, their mechanism of the coercivity is not yet completely understood. Recent studies revealed that the enhancement of coercivity could be realized by the nano-fabrication of the FePt thin film by electron beam (EB) lithography [1]. Therefore, it is thought that the microstructural control is promising way for improvement of coercivity for the Nd-Fe-B sintered magnets. In this study, in order to understand the coercivity mechanism, the various patterns of Nd-Fe-B thin films have been fabricated by microfabrication and the effect of cap layers on the magnetic properties have also investigated.

The samples were prepared by using an ultra-high vacuum magnetron sputtering system. The compositions of the Nd-Fe-B layer were controlled by co-sputtering with Fe, Fe80B20 (at.%), and Nd targets. Thus, the various patterns of Nd-Fe-B were microfabricated through the use of EB lithography followed by Ar ion etching. The structural analysis was performed by X-ray diffraction (XRD) with Cu Kα radiation. The magnetic properties were measured by superconducting quantum interference device (SQUID) magnetometer and magneto-optical Kerr effect (MOKE). The size and the shape of dots and the distance between the dots were confirmed by atomic force microscope (AFM) with dynamic force mode (DFM). The magnetic domain structure was observed by magnetic force microscope (MFM).

It is confirmed that well-defined shape of the Nd-Fe-B circular dot arrays have been successfully prepared by the microfabrication process as shown in Fig. 1. The reduction of coercivity was observed after deposition of cap layers such as Mn, Pt and Mo, however, the value of coercivity didn’t change after microfabrication for the case with Al cap layer to the circular dot arrays (11.3 kOe). The results of the pseudo-grain boundary phase varied from 10 to 100 nm in width of Nd-Fe-B square patterns will be discussed at the conference.

[1] D. Wang, T. Seki, K. Takanashi, T. Shima, G. Li, H. Saito and S. Ishio, IEEE Trans. Magn., 44, 3464 - 3467 (2008).

Fig. 1 AFM images for Nd-Fe-B circular dot arrays after deposition of Al cap layer.

B-42

PA-05

Field-driven Domain Wall Motion in Ferromagnetic Nanowires with Bulk Dzyaloshinskii-Moriya Interaction

Zhouzhou Sun and Fengjun Zhuo

College of Physics, Optoelectronics and Energy，Soochow University, Suzhou, Jiangsu 215006, China

Field-driven domain-wall (DW) motion in ferromagnetic nanowires with easy-

and hard-axis anisotropies was studied theoretically and numerically in the presence of

the bulk Dzyaloshinskii-Moriya interaction (DMI) based on the

Landau-Lifshitz-Gilbert equation. We proposed a new trial function and found an exact

solution for the DW motion along a uniaxial nanowire driven by an external magnetic

field. DW motion in a uniaxial magnetic nanowire can then be speeded up with large

DMI parameters. In the presence of the hard-axis anisotropy, we found that the

breakdown field and DW velocity was strongly affected by the strength and sign of the

DMI parameter under external fields. The work may be useful for future magnetic

information storage devices based on the DW motion.

B-43

PA-06

Synthesis and magnetic characterization of NiO-Ni core-shell nanotube arrays

Z.W. Zhang (a), T. Yu* (a), Y. Liu(b), Y. H. Xu (a), W. J. Li (c), X. F. Han(c) (a) College of Physical Science and Technology, Sichuan University, Chengdu

610064, China (b) Analytical & Testing Center, Sichuan University, Chengdu, 610064, China

(c) Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China

e-mail: work_tian@scu.edu.cn

The exchange bias (EB) coupling between ferromagnetic (FM) and antiferromagnetic (AFM) layers has attracted great interest for its applications in spintronic and high-density magnetic recording devices [1]. Recent advances have turned the focus on the AFM–FM interface into a low dimensional framework, especially into nanotubes and nanowires, where the magnetic properties are very novel duo to the high aspect ratio [2]. In previous, various FM and AFM nanotubes have been reported [3]. However, there are few discussions about exchange bias effects in AFM-FM core-shell nanotubes. In this paper, we investigate the synthesis and magnetic properties of NiO-Ni core-shell nanotube arrays. Well aligned Ni nanotubes with tunable length and wall thickness are fabricated in a porous anodic aluminum oxide (AAO) template by means of potentiostatic electrodeposition, followed by thermal oxidation of the inner wall in the air condition with magnetic field of 500 Oe. The thickness of NiO is controlled by annealing temperature and time. We characterize the sample morphology, structure and magnetic properties by scanning and transmission electron microscopy (SEM/TEM), x-ray diffraction (XRD)，vibrating sample magnetometer (VSM) and SQUIDE. The phase diagrams of exchange bias in our NiO-Ni core-shell nanotubes on annealing temperature and annealing time are summarized.

This work was supported by the National Natural Science Foundation of China [NSFC, Grant No. 11504249] and the Youth Foundation of Sichuan University.

[1] J. Nogues and I. K. Schuller, “Exchange bias,” J. Magn. Magn. Mater., vol. 192, pp. 203-232, Feb.1999.

[2]X. F. Han et al, “Structural and Magnetic Properties of Various Ferromagnetic Nanotubes,” Adv. Mater., vol. 21, pp. 4619–4624, Sep. 2009.

[3]M. P. Proenca, J. Ventura, C. T. Sousa, M. Vazquez and J. P. Araujo, “Temperature dependence of the training effect in electrodeposited Co/CoO nanotubes,” J. Appl. Phys., vol 114, 043914, July.2013.

Fig.1 SEM image of nanotube arrays

B-44

PA-07

Various properties of Fe-Co magnetic films prepared by

PLD method

A. Yamashita, M. Nakano, A. Kurosaki, T. Yanai, and H. Fukunaga

Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan e-mail: bb52114255@ms.nagasaki-u.ac.jp

Although a high speed PLD (Pulsed Laser Deposition) method is attractive in order to

obtain thick film rare-earth permanent magnets such as Nd-Fe-B and Pr-Fe-B films applied to miniaturized devices [1][2], the fundamental mechanism of the deposition process is still unclear. In this study, we focused on the preparation of Fe-Co films by using the PLD because a Fe-Co film has a simple binary-alloy-based composition. This contribution reports the relationship between the laser energy density (LED) of the PLD method and various values such as surface morphology, compositions and magnetic properties in PLD-fabricated Fe-Co films.

In order to control LED, we varied the spot size of a laser beam. Figure 1 shows the surface morphology of Fe-Co films prepared by using two different values of LED. The density higher than 10 J/cm2 enabled us to extremely reduce the number and/or size of droplets compared with the sample prepared by using the density less than 1 J/cm2. It was found that the use of a small spot size of laser beam (LED > 10 J/cm2) is effective to improve the surface roughness. Furthermore, the composition of a film prepared by LED > 10 J/cm2 tended to increase the Fe contents compared with that of a corresponding target. We also confirmed that the magnetic polarization of an obtained Fe71Co29 film prepared by using LED > 10 J/cm2 was approximately 2.4 T at applied magnetic field of 1400 kA/m. Resultantly, the PLD with high laser energy density (LED > 10 J/cm2) is a promising method for obtaining a Fe-Co film with high saturation magnetic polarization together with good surface morphology.

[1] M.Nakano et al, IEEE Transactions on Magnetics, 43, 2672-2676(2007)

[2] M.Nakano et al, Journal of Applied Physics, 115, 17A741-1~3(2014)

Fig.1 Surface morphology of samples prepared by using two values of LED.

B-45

PA-08

NEXAFS investigations of C60 / 3d -transition metal

interfaces

Kun-Ta Lu, Pei-Yu Cheng, Yuet-Loy Chan, Yao-Jane Hsu, Chun-I Lu , Tzu-Hung Chuang and Der-Hsin Wei

National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan

e-mail:lu.kane@nsrrc.org.tw

Physical properties of organic-metal contacts are subjects of interest in organic electronics and spintronics. With a better understanding on the electronic structures of the interface of metallic electrode and organic spacer, scientists hope to find ways to improve the carrier injection and detection efficiency so that hybrid devices with performance comparable to inorganic ones can be realized. In this study, we employ the near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to investigate the electronic structure of C60/3d-transition material interfaces [1]. Three series of bilayers with each series consist of a 0.36 nm-thick metal film (Fe, Co, or Ni) deposited on a set of C60 bottom layers (2 – 40 nm) were fabricated in-situ to allow systematic investigations on the metal contact and the thickness dependence of organics spacer. According to the Carbon K-edge NEXAFS spectra (see Fig. 1), we found clear evidence of orbital hybridization between C60 and the transition metals ,the LUMO+1 and LUMO+2 show notable variations. In addition, the L3-edge intensities of transition metal showed an unexpected C60 thickness dependence (see Fig. 2). Model analysis suggests that such thickness dependence is consistent with the scenario of metal atoms/clusters diffusing into organic layers. Satellite peaks are observed in the NEXAFS spectra of Fe/Co/Ni, and the deposition rate is modified to see how cluster size affects the spectra. Finally, detailed spectral analysis reveals subtle differences regarding the diffusion of Fe, Co, and Ni atoms/clusters within C60 film.

[1] P.Y. Cheng, M.R Chiang, Y.L. Chan, Y.J. Hsu, P.C. Wang and D.H. Wei, Appl. Phys. Lett. 104, 043303 (2014).

Fig. 2 Normalized NEXAFS spectra of

Fe, Co, and Ni

280 290 300 310

C60 (15 nm)

Ni on C60 (2 nm)

To

tal

Ele

ctr

on

Yie

ld

(no

rmal

ized

)

Photon Energy (eV)

Ni on C60 (30 nm)

280 290 300 310

C60 (15 nm)

Fe on C60 (2 nm)

To

tal

Ele

ctr

on

Yie

ld

(no

rmal

ized

)

Photon Energy (eV)

Fe on C60 (30 nm)

280 290 300 310

C60 (15 nm)

Co on C60 (2 nm)

To

tal

Ele

ctr

on

Yie

ld

(no

rmal

ized

)

Photon Energy (eV)

Co on C60 (30 nm)

Fig. 1 Carbon spectra of Fe, Co, and Ni

on 2/30 nm C60

B-46

PA-09

Effect of compositional modulation on the structure and magnetic properties for Mn-Al thin films

N. Kumagai, H. Iwama, M. Doi, and T. Shima

Department of Engineering, Tohoku Gakuin University, Tagajo, Japan Email : s1594303@g.tohoku-gakuin.ac.jp

Recently, the consumption of Nd-Fe-B sintered magnets [1] has increased due to the

utilization for hybrid and electric vehicles. However, due to the source natural resource of key elements such as Dy and Tb, a lot of efforts have been done to find another permanent magnet materials instead of rare earth based alloys. One of the candidate materials is Mn-based alloys. Among them, Mn-Al alloy with ferromagnetic τ-phase has been received much attention [2] because of its high magnetic anisotropy [3] and low material cost. In this study, the Mn-Al thin films have been fabricated on various composition and their structure and magnetic properties have been investigated.

The samples were prepared by using an ultrahigh vacuum magnetron sputtering system. The base pressure is below 8.5 × 10-7 Pa. High-purity argon of 0.2 Pa was introduced during sputtering. First of all, Cr buffer layer was deposited onto MgO (100) single crystal substrates. Them, Mn-Al layer was deposited at Ts = 400 ºC. The composition of the Mn-Al thin films were varied and determined by electron probe X-ray micro-analysis (EPMA). The structural analysis was performed by X-ray diffraction (XRD) with Cu Kα radiation. The magnetization curves were measured using a superconducting quantum interference device magnetometer (SQUID) in the field up to ± 70 kOe.

Magnetization curves for Cr (20 nm)/ Mn52.9Al47.1 (40 nm)/ Mn46.8Al53.2 (40 nm)/ Cr (20 nm) thin films with different are shown in Fig. 1. Considerably large Ms of 510 emu/ cm3

was obtained at the Mn52.9Al47.1/ Mn46.8Al53.2 film. However, the coercivity was decreased compared to single layer films. The detail results about the structure and magnetic properties will be discussed at the conference. [1] M. Sagawa, S. Fujimura, N. Togawa, H.Yamamoto, Y. Matsuura, J. Appl. Phys., 55, 2083 (1984). [2] H. Kono, J. Phys. Soc. Jpn., 13, 1444 (1958). [3] A. Sakuma, J. Phys Soc. Jpn., 63, 1422 (1994).

Fig. 1 M-H curves for Cr (20 nm)/ Mn52.9Al47.1 (40 nm)/ Mn46.8Al53.2 (40 nm)/ Cr (20 nm) thin film.

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PA-10

Structural and Magnetic Properties of FeCo thin films

N. Inami(a), T. Ueno(b), T. Hasegawa(c), S. Ishio(c), and K. Ono(a)

(a)Institute of Materials Structure Science, KEK, Tsukuba, 305-0801, Ibaraki, Japan (b)ESICMM, NIMS, Tsukuba, 305-0047, Ibaraki, Japan

(c)School of Engineering, Akita University, 010-8502, Akita, Japan e-mail: nobuhito.inami@kek.jp

Magnetic materials which do not contain rare metals have been extensively studied. Fe-Co alloy is one of the candidates with both high magnetocrystalline anisotropy and high saturation magnetization. The magnetocrystalline anisotropy of body centered tetragonal type Fe-Co alloys has been reported by first-principles calculation. [1] In addition, the largest anisotropy has been realized at the lattice parameters ratio c/a of about 1.25. [2] However, the additional elements to FeCo alloy or epitaxial growth on a buffer layer [3] for introducing lattice distortion have been still intensively studied, since the introduction of lattice distortion is rather difficult. In this study, we investigated the thickness dependence of the crystal structure and the magnetic properties.

The FeCo thin films of 0.5 – 20 nm thickness were deposited on MgO substrates with 20 nm Rh buffer layer and 2 nm Ru cap layer by sputtering system. X-ray diffraction measurement was carried out with the photon energy of 7.1 keV under the Fe K-edge at BL-4C, BL-7C, and BL-8A/B of Photon Factory (PF) in KEK. X-ray magnetic circular dichroism measurement (XMCD) was performed at BL-16A of PF.

X-ray absorption and XMCD spectra of Fe and Co of 2 nm thickness FeCo film are shown in Fig. 1. L3 and L2 absorption edge peaks and XMCD signals are clearly observed. Spin and orbital magnetic moments of Fe and Co were calculated from the XMCD spectra by using sum rules. The spin and orbital magnetic moments of Fe were 1.68 and 0.20 and those of Co were 1.52 and 0.19. The orbital magnetic moment perpendicular to the substrate plane becomes maximum around the thickness of 2 nm. This result is approximately consistent with the magnetic properties measured by VSM.

This work was partly supported by Japan Science and Technology Agency (JST). [1] T. Burkert, et al., Phys. Rev. Lett. 93, 027203 (2004). [2] Y. Kota and A. Sakuma, Appl. Phys. Exp. 5, 113002 (2012). [3] H. Oomiya, et al., J. Phys. D: Appl. Phys. 48, 475003 (2015).

Fig. 1 XAS and XMCD of FeCo.

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PB-01

Intracellular nanoparticle-mediated hyperthermia of microscopic tumours

Chen-Yu Huang,(a) Ying-Chang Tsao,(b) Kuo-Wei Chiu,(a) Ching-Ming Lee,(b) Te-Ho Wu,(b) Ming-Shinn Hsu,(c)* Zung-Hang Wei(a)*

(a) Department of Power Mechanical Engineering, National Tsing Hua University,

Hsinchu City, Taiwan (b) Graduate School of Materials Science, National Yunlin University of Science and

Technology, Yunlin, Taiwan (c) Department of Obstetrics and Gynecology, Ching-Kuo Campus of Min-Sheng

Hospital, Taoyuan, Taiwan

*e-mail: mingshsu@gmail.com; wei@pme.nthu.edu.tw

Intracellular nanoparticle-based hyperthermia is said to be therapeutically superior to its extracellular counterpart for cancer treatment. [1] In nature biological system, primary cancer form a colony/cluster with before escaping into circulatory system to metastases. Therefore, evaluating the induced effects of intracellular hyperthermia treatment utilizing clusters of cancer would be more appropriate. Herein, simple experimental model evaluate the intracellular hyperthermia and its associated cytotoxicity using microscopic Jurkat tumorsphere. Paramagnetic nanoparticles (NPs) coating with anionic polymers are selected for the treatment (Fig.1 (a)). Cells were incubated nanoparticles at different concentrations. Prussian blue staining visualized the distribution of nanoparticles. Quantitative measurement of magnetic nanoparticles number was assessed by magnetophoresis. Cells were submitted to an alternative magnetic field (H=4 kA/m, f=21 kHz) and live/dead fluorescence assay analyzed the cytotoxicity effects at different exposure time. The particle number sufficient to induce cytotoxicity effects of Jurkat cell can be realized (Fig.1 (b)).

Fig.1 (a) TEM picture with magnetic NP size distribution (b) intracellular particle number versus viability after hyperthermia treatment for 180s. [1] R. T. Gordon, J. R. Hines, D. Gordon, Med Hypotheses., 5, 83 (1979).

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PB-02

New approach for quantitative single-cell analysis of magnetic labelling efficacy

Chen-Yu Huang,(a) Jing-Ci Su,(b) Te-Ho Wu,(b) Yi-Han Peng,(c) Zung-Hang

Wei(a)*

(a) Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City, Taiwan

(b) Graduate School of Materials Science, National Yunlin University of Science and Technology, Yunlin, Taiwan

(c) Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu, Taiwan

*e-mail: wei@pme.nthu.edu.tw

Iron oxide magnetic nanoparticles are commonly used to label cells for magnetic application.[1] Various approaches have been proposed to evaluate the magnetic labelling efficiency. [2] In this study, we demonstrate an approach to quantify cellular uptake of iron oxide nanoparticles at the single cell level. This method is based on analyzing the color of the selected single cell from the iron staining images and measuring the gray (Fig. 1). In the experiment, Human hepatocellular carcinoma cells (HepG2) were incubated with different concentrations of 10 nm magnetic nanoparticles and magnetically labeled by internalizing magnetic nanoparticle. Quantitative analysis results were compared to magnetophoresis experiment results and a noticeable agreement is shown in both methods. The method is applicable for analyzing the kinetic of magnetic labeling and the uptake capacity of the cell.

Fig.1 (a) Extracellular incubated MNP concentration versus the gray value of magnetically labeled cell post iron staining (b) gray value of cells post iron staining versus intracellular particle number versus. [1] M. F. Lai, C. Y. Chen, C. P. Lee, H. T. Huang, T. R. Ger, and Z. H. Wei, Appl. Phys. Lett., 96, 183701(2010) [2] C. Wilhelm, F. Gazeau, and J. Bacri, Eur. Biophys. J., 31, 118-125 (2002).

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PB-03

Three-Dimensional Magnetic Nanoparticle Imaging Using Multiple Pickup Coils

Y. Tsujita, M. Morishita, M. Muta, T. Sasayama, and K. Enpuku

Department of Electrical Engineering, Kyushu University, Fukuoka, Japan tsujita@sc.kyushu-u.ac.jp

Magnetic particle imaging (MPI) has been extensively studied for use in medical

diagnosis. In this application, magnetic nanoparticles (MNPs) accumulated in human (or animal) body are detected by measuring the magnetic signal from the particles.

We have been developing a narrow-band MPI system using third harmonic signal detection and field free line (FLL) of the gradient field. In the previous paper, we successfully demonstrated two dimensional MPI using this method [1]. However, it is necessary to extend the system to three dimensional MPI for practical use. For this purpose, we propose a method to use multiple pickup coils for signal detection.

In the present study, as a first step, we show three dimensional MPI using two pickup coils. In an experiment, two MNPs were placed at different positions as listed in Table I. Contour map of the signal field from MNPs was detected with two pickup coils. Then, distribution of MNPs was reconstructed by analysing the measured contour maps. We note that three dimensional MNPs distribution can be obtained by using different contour maps measured with two pickup coils.

Figure 1 shows the estimated MNPs distribution projected in x-y plane. We can clearly distinguish two MNPs. In Table I, estimated positions of two MNPs are shown. As shown, three dimensional positions of two MNPs are correctly evaluated with reasonable accuracy. Accuracy of reconstruction could be much improved by increasing the number of pickup coils.

[1] K. Enpuku et al, Jpn. J. Appl. Phys., 54, 057002 (2015).

Fig. 1. Reconstructed distribution of MNPs projected in x-y plane.

Table 1. Comparison between actual and estimated three dimensional positions of two MNPs samples.

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PB-04

Highly Sensitive Liquid-Phase Immunoassays Using Improved Magnetization Process of Magnetic

Markers

K. Nakamura, M. Ura, Y. Takafuji, T. Sasayama, T. Yoshida, and K. Enpuku

Department of Electrical Engineering, Kyushu University, Fukuoka, Japan

e-mail: nakamura@sc.kyushu-u.ac.jp

We have been developing a liquid-phase detection technique of biological targets using magnetic markers. In this method, markers bound to the targets (bound markers) and unbound (free) markers are magnetically differentiated by using the Brownian relaxation of free markers. Although highly sensitive detection of targets was demonstrated, blank signal from the free markers remained an issue for further improvement [1].

In our method, a large excitation filed of about Bmag = 40 mT is applied in order to generate magnetic signal from the bound markers. This magnetization process, however, causes aggregation of free markers, and generates the blank signal. Therefore, it is necessary to improve the magnetization process. For this purpose, we studied subjects that influence blank signal, such as (1) magnetization time Tmag, (2) concentration of markers, nm, and (3) dispersion process after magnetization. It was shown that the blank signal increases lineally with Tmag, while it increases with nm

2. It was also shown that the dispersion process using vortex steering is very effective to dissolve agglomerate of free makers caused by the magnetization field Bmag.

We optimized the magnetization process on the basis of above results. Figure 1 shows the detection of biotin molecules using the improved method. Horizontal axis represents the number of biotin molecules, NB, while the vertical axis represents the signal from the bound markers, Bs, detected with SQUID sensor. As shown, blank signal at NB = 0 became small compared to the previous result shown in [1]. The blank signal was about 3 times decreased by using the improved magnetization process. We obtained good relation between NB and Bs. The detection sensitivity was 1.8 × 10-19 mol/ml in terms of molecular number concentration, indicating high sensitivity of the present method. [1] K. Enpuku et al., IEEE Trans. Appl. Supercond. 24, 1600105 (2014).

05

10152025303540

0 2 4 6 8 10 12 14

Bs (

pT)

NB (104)

Blank

Fig. 1. Relationship between the number NB of biotin molecules and the detected signal Bs.

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PB-05

Single-Sided Magnetic Particle Imaging Using Planar Gradient Coil and Electric Scanning of Field Free Point

K. Yamamoto, K. Tanabe, Shi Bai, T. Sasayama, T. Yoshida, and K. Enpuku

Department of Electrical Engineering, Kyushu University, Fukuoka, Japan

e-mail: yamamoto@sc.kyushu-u.ac.jp

Magnetic particle imaging (MPI) is a new imaging technique that uses the nonlinear magnetic response of magnetic nanoparticles (MNPs). We have been developing a single-sided MPI system, where excitation and detection of MNPs are performed from one side of the human body. For this purpose, we developed a planar gradient coil made up of four pieces of a square coil, as schematically shown in Fig. 1(a). The field free point (FFP) of the gradient field occurred at the center of the coil: By using the FFP, we can improve the spatial resolution in MNPs detection. In the previous study, we demonstrated the MPI using this system, where MNPs sample was mechanically scanned to obtain a contour map of the signal field [1].

In this study, we present an MPI using an electrical scanning of the FFP in order to develop more practical system. Two shift coils were added as shown in Fig. 1(a), with which we can electrically move the FFP in the x-y plane. In an experiment, one MNPs sample was fixed at x = y = 0 in Fig. 1(a). Then, we applied an AC current with amplitude of 9 A and frequency of 2 Hz to the shift coils. In this case, we can electrically scan the FFP in a 32 × 32 mm area in approximately 10 s. Figure 1(b) shows the contour map of the signal field measured in this way. As shown, we obtained a clear contour map. The spatial resolution of the map was approximately 12 mm, which was determined by the field gradient of 0.4 T/m of the gradient coil.

(a) (b) Fig. 1. (a) Schematic figure of the planar gradient coil and shift coils. (b) Contour map of the signal field obtained with electric scanning of the FFP. [1] S. Bai et al., IEEE Trans. Magn. 50, 5101304 (2014).

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PB-06

Modeling of the Retardance in Citric Acid Coated Ferrofluids Using Stepwise Regression

Jing-Fung Lin(a), Jer-Jia Sheu(b)

(a) Department of Innovative Design and Entrepreneurship Management, Far East University, No.49, Zhonghua Rd., Xinshi Dist., Tainan City 74448, Taiwan

(b) Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, No. 1, Nan-Tai Street, Yungkang Dist., Tainan City 71005, Taiwan

e-mail: jacklin@cc.feu.edu.tw

Citric acid (CA) coated Fe3O4 ferrofluids (FFs) have been conducted for biomedical application. The magneto-optical retardance of FFs was measured by a polarimeter [1]. Optimization and multiple regression of retardance in FFs were executed by Taguchi method and Excel, and the F value of regression model was large enough [1]. However, the modeling of retardance executed by Excel is not in a systematic way. In stepwise regression, a stepping procedure which iteratively altering the model established at the previous step by adding or removing variables in accordance with the stepping criteria is used in order to add significant variables or remove insignificant variables [2]. The results of stepwise regression by MATLAB was shown in Fig. 1, the model had highly predictable ability owing to F of 2.55897e+7 and had a high correlation coefficient of one. The average absolute error of predicted reatrdances was just 0.0044%.

Based on the regression equation, the evolutionary solver in Excel was used to solve optimization problems. The optimized combination was obtained as [4.7037 0.12 39.99991 70.0021], i.e. pH of suspension, molar ratio of CA to Fe3O4, CA volume, and coating temperature and the maximum retardance was 31.716°. Also, the genetic algorithm (GA) in MATLAB was used to solve optimization problems. As shown in Fig. 2, the optimized combination and maximum retardance are determined as [4.709 0.12 39.998 70.006] and 31.712°, close to those by Excel and a relative error of -0.013%. Above all, we successfully model the retardance in CA coated FFs by stepwise regression and the maximum global retardance is determined by the GA.

Fig. 1 Results of stepwise regression. Fig. 2 Output using the GA in MATLAB.

[1]J. F. Lin, J. S. Wu and J. J. Sheu, Proc. of SPIE, 9302, 930229 (2015). [2]L. Jiao, H. Li, Chemometrics and Intelligent Laboratory Systems, 103, 90 (2010).

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PB-07

Paramagnetic Ions Dy3+ Doped Ultrathin Shell of SiO2@Gd2O3 Nanoparticles as a Potent Agent for

Magnetic Resonance Imaging

J. C. Yin, C. R. Li and Y. Z. Shao* State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics

＆ Engineering, Sun Yat-sen University,Guangzhou 510275, P. R.China. *e-mail:stssyz@mail.sysu.edu.cn

Rare earth ions Dy3+, which possess the highest ionic magnetic moment, were doped into the ultrathin Gd2O3 nanoshells of around 4nm thickness coated on the surfaces of amorphous SiO2 nanocores by a facile coprecipitation method. Considering that ultrasmall Gadolinium Oxide could transmigrate the blood-brain barrier and easily aggregated[1], we prepared core-shell structured SiO2@Gd2O3:Dy3+ nanoparticles of approximitely 94.5nm in an average diameter with a uniform size distribution, which are quite close to sphericity and possess the superior dispersibility(Fig.1). Doping appropriate Dy3+ ions accounted for high longitudinal and transverse relaxivities. The measured T1 relaxivities of the samples were more than 7 times higher than the relaxivity of the commercial contrast agent Gd-DTPA in a 0.55T MR(magnetic resonance) system(Fig.2). Electromagnetic properties of these nanoparticles with the different amounts of doped Dy were detected by superconducting quantum interference device(SQUID). In vitro cytotoxicity tests based on the cck-8 assay revealed the low toxicity and satisfactory biocompatibility. The nanocomposites investigated in this study have a high potential to be developed into the safe and effective novel contrast materials. [1]Y. Z. Shao et al., Biomaterial, 33(2012) 6438.

Fig.1 Structure of SiO2@Gd2O3:Dy3+ Fig.2 Dependence of r1 and Dy%

0.00 0.02 0.04 0.06 0.08 0.10

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 2 3 4 55

10

15

20

25

30

35

40

r 1 (

s-1m

M-1)

1.0mol%

0.5mol%

0.1mol%0mol%1.5mol%2.0mol%5.0mol%

Gd-DTPA r

1=4.2

1/T

1 (

s-1)

Gd3+ concentration (mM)

Dy3+

concentration (mol%)

SiO2@Gd

2O

3:Dy3+

r1max

=33.76

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PB-08

Influence of annealing temperature on structural and magnetic properties of LaMnO3 nanoparticles

Pardi S. Tola(a), D. H. Kim(a), Chunli Liu(a), T. L. Phan(a), and B. W. Lee(a,b)

(a) Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin, Gyeonggi 449-791, South Korea

(b) e-mail: bwlee@hufs.ac.kr

It is known that stoichiometric LaMnO3 is an A-type antiferromagnet with the Néel temperature TN = 135~140 K. Recently, the thin films and nanoparticles based this material have attracted intensive interest because its magnetic and electrical properties can be controlled in a large temperature range from 60 to 300 K upon tuning the vacancies of cation and/or oxygen in non-stoichiometric compounds of La1-xMn1-yO3±δ, leading the mixed valence of Mn2+, Mn3+ and/or Mn4+ ions [1, 2]. Particularly, with non-stoichiometric compounds, one can easily fabricate transparent ferromagnetic conducting thin films [1]. To get more insight into this problem, we fabricated LaMnO3

nanoparticles (NPs), and then studied the influence of annealing temperature on structural and magnetic properties of NPs. Here, LaMnO3 NPs were synthesized from precursors of lanthanum(III) acetate sesquihydrate, and manganese(II) acetate tetrahydrate by using a sol-gel method. As-prepared NPs were then annealed at different temperatures (Tan) of 600-1550 oC for 4 h in air. Crystal-structural analyses based on X-ray diffraction patterns revealed the samples annealed at 600-1400 oC crystallized in a rhombohedral structure with R-3c space group, with the ratio of the cation La/Mn varying from ~0.916 for Tan = 600 oC to 0.887 for Tan = 1400 oC. Meanwhile the sample annealed at 1550 oC crystallized in an orthorhombic structure. By changing Tan, we fabricated LaMnO3 particles with average sizes of 16-3000 nm, which were estimated by using the Scherrer equation and scanning electron microscope. Magnetization measurements indicated their ferromagnetic-paramagnetic phase transition temperature (TC) can be tuned in the range between 43 and 260 K. At 15 K, the saturation magnetization (Ms) and coercivity (Hc) values are tunable in the ranges of 4~84 emu/g and 25~1300 Oe, respectively. We think that these changes in magnetism of NPs versus Tan are due to the changes in the concentration of Mn3+ and Mn4+ ions, lattice parameters, local geometrical structures, and grain sizes.

[1] J.M. Vila-Fungueiriño, B. Rivas-Murias, B. Rodríguez-González, O. Txoperena, D. Ciudad, L.E. Hueso, M. Lazzari, F. Rivadulla, ACS Appl. Mater. Interfaces, 7, 5410 (2015). [2] J. Topfer, J.B. Goodenough, J. Solid State Chem., 130, 117 (1997).

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PC-01

Effects of Mg-doping on magnetic and dielectric properties of magnetoelectric GaFeO3 nanocrystals

Yi-De Chung, Chun Yun, and Tai-Chun Han

Department of Applied Physics, National University of Kaohsiung, Kaohsiung 81148,

Taiwan e-mail: tchan@nuk.edu.tw

Gallium ferrite, GaFeO3 (GFO), has ferrimagnetic (FM) and piezoelectric orderings and has been intensively studied recently for its potential application as a magnetoelectric ferrimagnet [1]. Site-disorder in bulk GFO is reported to be induced by adopting different preparation conditions and methods, which are shown to affect the magnetic properties significantly [1-3]. Moreover, the physical properties of GFO at reduced grain sizes remain underexplored due to the challenges associated with their synthesis with a proper control over the crystalline phase. In addition, the origin of the doping effects on the correlation between the site-disorder and magnetism in the nanosized GFO system has not yet been completely established. Therefore, it is worthy to explore the possibility of tuning the magnetic properties of doped GFO nanoparticles. In this work, we prepare a series of Ga1-xMgxFeO3 (GMFOx) (0 x 0.1) nanoparticles by a modified Pechini method to systematically study the effect of Mg-doping on their structural, magnetic, and dielectric properties. Interestingly, the magnetization and electric polarization of the doped samples are enhanced compared to those of the pristine sample of GFO. The magnetic hysteresis curves measured below the FM transition temperature (TC) exhibit two-phase-like magnetic behavior consisting of soft and hard magnetic phases. The results could be explained by the site-disorder of the cations in GMFOx. Furthermore, thermo-magnetic irreversibility and cusp in zero-field cooled magnetization are observed for all the GMFOx nanocrystals, which are attributed to the inherent magnetic anisotropy. Moreover, variable temperature dielectric measurements show an anomaly in the dielectric constant at the temperature close to the TC indicates the magnetoelectric coupling of the GMFOx nanocrystals. These results open wide perspectives for the room temperature FM magnetoelectric GFO ferrite in spintronic devices. References: [1]. T. Arima, D. Higashiyama, Y. Kaneko, J. P. He, T. Goto, S. Miyasaka, T. Kimura, K.

Oikawa, T. Kamiyama, R. Kumai, and Y. Tokura, Phys. Rev. B 70, 064426 (2004). [2]. M. B. Mohamed, A. Senyshyn, H. Ehrenberg, and H. Fuess, J. Alloys Compd. 492,

L20 (2010). [3]. K. Sharma, V. R. Reddy, D. Kothari, A. Gupta, A. Banerjee, and V. G. Sathe, J. Phys.:

Condens. Matter 22, 146005 (2010).

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PC-02

Fig.1(a). M-T curves at 100 Oe field and inset shows χ´-T at different f. (b) M-H loop at 2 K, and inset shows the HEB vs. T curve.

Observation of spin glass behaviour and large exchange bias in Mn-Ni-Co-Sn Heusler Alloy

Jyoti Sharma and K. G. Suresh

Department of Physics, Indian institute of Technology Bombay, Mumbai, India email: jyotisharma@iitb.ac.in

In recent years, Ni-rich (50 at.%) Ni-Mn-Z (Z= Ga, Sb, In, and Sn) Heusler alloys have attracted much attention due to their potential applications in magnetic refrigeration and spintronic devices. They exhibit multifunctional properties, such as giant magnetocaloric effect and exchange bias (EB), owing to their first order structural (martensitic) transition [1-2]. In contrast to Ni-Mn-Z Heusler alloys, Mn rich (50 at.%) Mn-Ni-Z Heusler alloys have not been investigated extensively so far. In present work, we have investigated magnetic and EB properties of Mn50Ni36Co6Sn8 Heusler alloy. Low temperatures magnetic state of martensitic phase has been studied by means of DC magnetization and AC susceptibility measurements, which shows the presence of spin glass (SG) state at low temperatures. Fig. 1(a) shows ZFC, FC and FH, magnetization vs. temperature curves, at 100 Oe. Alloy undergoes the martensitic transition at ~333 K. At low temperatures, a large splitting between ZFC and FC curves is observed, which indicates the presence of SG [3]. To investigate SG state, AC susceptibility vs. temperature curves were recorded, at different frequencies (f) (shown as inset of Fig. 1(a)). Peak temperature (Tf) observed in χ´-T curves are found to shift to higher temperatures with increase in f, which indicates the presence of SG. The observation of memory effect and relaxation measurements confirmed the SG state. Magnetic hysteresis (M-H) loop were recorded at different temperatures after FC process at 10 kOe, as shown in Fig. 1(b). A large EB field (HEB) of ~990 Oe has been observed for this alloy, which is significantly larger than those reported for other Co doped Heusler alloys [2]. Temperature dependence of HEB is shown in inset of Fig. 1(b), in which HEB decreases with increasing temperature. This large EB is attributed to the large exchange anisotropy created at SG/AFM interfaces. Thus present study facilitates in the search of new Heusler alloys with large EB properties.

[1] M. Pasquale, C. P. Sasso, L. H. Lewis, L. Giudici, T. Lograsso and D. Schlagel, Phys. Rev. B, 72, 094435 (2005). [2] A. K. Nayak, K. G. Suresh and A.K. Nigam, J. Phys. D, Appl. Phys. 42, 115004 (2009).

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PC-03

Giant magnetocaloric effect in manganite perovskites La0.7Ca0.3Mn1-xCuxO3

T. A. Ho(a), T. L. Phan(b) and S. C. Yu(c), S. H. Lim(a)

(a) Department of Materials Science and Engineering, Korea University, Seoul, 136-713, South Korea

(b) Department of Physics, Hankuk University of Foreign Studies, Yongin 449-791, South Korea

(c) Department of Physics, Chungbuk National University, Cheongju 361-763, South Korea

e-mail: sangholim@korea.ac.kr

The magnetic properties and the magnetocaloric effect (MCE) of pollycrystalline La0.7Ca0.3Mn1-xCuxMnO3 (x = 0.0, 0.04, 0.06, and 0.08) were investigated. Detailed analyses of magnetic-field dependences of magnetization at temperatures around the paramagnetic-ferromagnetic transition, M(H, T), reveal that the samples with x = 0.0, 0.04, 0.06 undergo a first-order magnetic phase transition (FOMT) while the last sample with x = 0.08 have a coexistence of the FOMT and second-order magnetic phase transition (SOMT) nature. Magnetic entropy changes (ΔSm) were calculated from magnetization data using Maxwell’s relation. For all the samples, the maximum magnetic-entropy change (|∆Smax|) occurs near Curie temperature (TC). With ΔH = 50 kOe, |∆Smax| values are about 10.3, 9.5, 7.7, and 4.8 Jkg-1K-1, corresponding to the relative cooling power (RCP) are about 290, 295, 305, and 360 Jkg-1, for x = 0.0, 0.04, 0.06 and 0.08, respectively. Clearly, with an appropriate Cu-doping concentration, it can be increased remarkably the RCP of La0.7Ca0.3Mn1-xCuxMnO3 compounds compared to the parent compound La0.7Ca0.3MnO3. This indicates the possibility of tuning the |∆Smax|-peak position and RC value for magnetic refrigeration applications.

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PC-04

Magnetostriction and magnetic domain structure in an Fe-Ga alloy single crystal grown

by the Czochralski method

S. Asano(a), S. Fujieda(a), T. Fukuda(b), K. Ishiyama(c) S. Suzuki(a) (a) Institute of Multidisciplinary Research for Advanced Materials, Tohoku University,

Sendai 980-8577, Japan (b) Fukuda Crystal Laboratory, Sendai 989-3204, Japan

(c) Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan

Fe-Ga alloys are gathering much attention because of good machinability and superior

magnetostrictive property for application to actuators and vibration energy harvesters. Recently, Fe-Ga alloy single crystals were successfully grown by the Czochralski (CZ) method [1]. In this study, the relationship between the magnetostrictive property and magnetic domain structure in an Fe-16 at%Ga alloy single crystal grown by the CZ method was investigated. To evaluate the magnetostrictive property, a strain gauge was attached on the (001) plane in the [100] direction. The magnetic domain structure on the (001) plane was observed by a magneto-optic Kerr effect microscope. In the mentioned-above experiments, magnetic fields were applied in the [100] direction on the plane. Figure 1 shows the magnetostriction curve of the specimen. The magnetostriction rapidly increases in the vicinity of 1250 Oe with increasing magnetic field and reaches the saturation value of about 109 ppm at about 2000

Oe. As shown in Fig. 2, 90° domain walls are aligned with the <110> direction at zero magnetic field. Additionally, 180° domain walls form a staircase-like structure. When a magnetic field was applied along the [100] direction, 180° domain walls primarily moved, and they almost disappeared at about 1100 Oe. In other words, a striped domain structure composed of 90° domain walls was observed. The single domain structure was obtained after motion of 90° domain walls under the magnetic field above about 2000 Oe. Therefore, the mentioned-above change of magnetic domain structure corresponds to the magnetostrictive property. It is clear that 180° domain walls easily moved compared to 90° domain walls by applying the magnetic field in the Fe-16 at%Ga alloy single crystal. [1] S. Fujieda et al., IEEE Trans. Magn. 50, 2505204 (2014).

Fig. 1. The magnetostriction curve in the [100] direction

Fig. 2. Magnetic domain structure on the (001) plane under zero magnetic field

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PC-05

The exchange effect of paired-electrons in superconductivity

Ke-Chuan Weng(a) (b) and C. D. Hu(b) (a)Research Center for Applied Sciences, Academia Sinica, Taipei Taiwan 11529

(b)Department of Physics, National Taiwan University, Taipei, Taiwan 10617 The electron-electron exchange effect plays an important role in the electron-electron scattering

process. In QED, we have known that exchange effect in electron-electron scattering would result in a minus sign relative to the original scattering process. We discuss the exchange effect of pair electrons in superconductor. The electron-electron exchange influences the electron-electron scattering differently for differently spin pairing configuration. For BCS cooper pair, pair electrons with opposite spin, the phonon mediated scattering could not flip electron spin and hence the exchange effect is absence in this phonon mediated scattering. For photon mediated scattering, the flip of electron spin is permitted and the exchange effect should be considered. However, in the non-relativistic limit, the spin un-flipped scattering processes dominate the scattering. The spin flip scattering is O(v^2/c^2 ) smaller than the spin un-flipped scattering processes and the exchange effects in such spin pairing electrons scattering is suppressed. For equal spin pairing electrons, the exchanged scattering is equally important to the original un-exchanged process for both phonon and photon mediated process. However, there is an extra minus sign relative to the original scattering process. We suggest that this extra minus sign is important in resulting the odd gap function for the pair electrons with equal spin pairing, such as p-wave and f-wave superconductors.

Fig. 1 The photon mediated scattering process. Both scattering process are permitted, the exchange effect should be considered. However, the spin flipped scattering process is supressed with O (v2/c2) smaller than the spin un-flipped scattering process. Hence, the spin un-flipped scattering processes dominate the electron scattering. For opposite spin pairing, only one of both figure (the spin un-flipped one) is important. For equal spin pairing, both scattering processes are spin un-flipped scattering process and equally important. The contribution of both scattering process in equal spin pairing would result in the odd gap function.

Fig. 2 The phonon mediated scattering process. For equal spin pairing, s=r and s'=r', both spin preserved (s=s' and s=r' ) scattering process should be included. For opposite spin pairing (s≠r and s'≠r' ), either one (s=s' or s=r') of both scattering process is permitted but not both.

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PC-06

Magnetic properties of the ternary stannides Sm3Co4Sn13

and Tb3Co4Sn13

Chia-Nung Kuo, Chang-Miin Wang , Chin-Shan Lue

Department of Physics, National Cheng Kung University, Taian, Taiwan e-mail: kuochianung@gmail.com

Single crystals of Sm3Co4Sn13 and Tb3Co4Sn13 are synthesized using tin flux method [1]. Sm3Co4Sn13 and Tb3Co4Sn13 of the Yb3Rh4Sn13 type crystallize in the cubic nPm3 space group with the lattice parameters a ~ 9.515 Å and 9.464 Å. In contrast to the previous DFT calculations [2], the temperature-dependent magnetic susceptibility data show that both Sm3Co4Sn13 and Tb3Co4Sn13 order antiferromagnetically at TN ~ 7.8 K and 11.4 K. Temperature dependence of ZFC and FC magnetizations for Sm3Co4Sn13 shows a weak ferromagnetic behavior at 62 K. The effective moment of the Sm and Tb analogues were determined as 0.72 µB and 9.54 µB which are close to the calculated effective moment of R3+ ions. The trend of AFM ordering temperatures of R3Co4Sn13 is proportional to the de Gennes factor.

[1] H. F. Liu, C. N. Kuo, C. S. Lue, K.Z. Syu, and Y. K. Kuo Phys. Rev. B 88, 115113 (2013) [2] Guohua Zhong, Xiaowu Lei, and Jianggao Mao Phys. Rev. B 79, 094424 (2009)

B-62

PC-07

High Field X-ray Diffraction Measurements in

Mn2Sb0.9Sn0.1

Taoto Wakamori(a), Yoshifuru Mitsui(a), Kohki Takahashi(b), Rie Y. Umetsu(b), Masahiko Hiroi(a), Keiichi Koyama(a)

(a) Graduate School of Science and Engineering, Kagoshima University, Kagoshima

890-0065, Japan (b) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

e-mail: k2914897@kadai.jp

Mn2Sb with a Cu2Sb-type tetragonal structure is a ferromagnetic below TC ~ 550 K [1]. The substitution of various elements (V, Cr, Co, Cu, and Zn) for Mn, as well as (Ge and Sn) for Sb, result in a first-order magnetic transition from a ferromagnetic (FRI) to an antiferromagnetic (AFM) state with decreasing temperature T [1-4]. Recently, the dynamics of the FRI-AFM transition in Mn2-xCoxSb was reported to be arrested by applying a magnetic field B, the so-called kinetic arrest effect (KA effect) [3]. On the other hand, Mn2Sb1-xSnx did not exhibit KA effect in B [4]. In this work, high field X-ray powder diffraction (HF-XRD) measurements were performed for Mn2Sb0.9Sn0.1 in order to clarify the structural properties in magnetic fields.

Fig. 1 shows the HF-XRD profiles (004 diffraction) in 55.5o ≤ 2θ ≤ 58.0o at several temperatures under a zero field and 5 T. As seen in Fig.1(a), under B = 0 T, the peak intensity of the AFM phase () was confirmed only for 10 ≤ T < 150 K. The diffraction peak of the FRI phase () appeared for T ≥ 130 K, and the two-phase coexistence of the AFM and FRI phases is observed for 130 ≤ T ≤ 150 K. Below 105 K, the AFM phase was only confirmed. As seen in Fig. 1(b), under B = 5 T, the AFM phase appeared in T < 130 K. However, the residual FRI phase did not disappear even in field cooling at low temperature. This result suggests that Mn2Sb0.9Sn0.1 also show KA effect from the viewpoint of structural properties. It was observed that magnetic relaxation behavior from FRI to AFM state in 10 ≤ T ≤ 50 K by magnetization measurements, which was analyzed using Kohlrausch-Williams-Watts model. References [1] M. K. Wilkinson, et al., J. Phys. Chem. Solids 2 (1957)

289. [2] T. Kanomata and H. Ido, J. Appl. Phys. 55 (1984) 2039. [3] H. Orihashi et al., Mater. Trans. 54 (2013) 969. [4] D. Shimada et al., J. Korean Phys. Soc. 63 (2013) 747.

Fig.1 XRD profiles of Mn2Sb0.9 Sn0.1 under 0 T (a) and under 5 T (b).

B-63

PC-08

Magnetic Response of hybrid ferromagnetic and antiferromagnetic core-shell nanostructures

U. Khan, W. J. Li, N. Nairan, M. Irfan, C. H. Wan, K. Javed, D. W. Shi, and X. F. Han*

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy

of Sciences, Beijing, 100190, China. *xfhan@iphy.ac.cn

One-dimensional (1D) nanocylinders including nanowires (NWs) and nanotubes (NTs) have attracted

considerable scientific interest during the last decade because of their potential applications in sensors, microwave absorption, biological separation and high density recording media. Simultaneous existence of more than one ferroic order such as ferromagnetic, ferroelectric and ferroelastic orders in multiferroics demonstrates significant technological promise in novel multifunctional devices [1-4]. The synthesis of FeTiO3-Ni(Ni80Fe20) core-shell nanostructures by two step method (sol-gel and DC electrodeposition) has been demonstrated. XRD analysis proved the rhombohedral crystal structure of FeTiO3(FTO) with space group R3 . Transmission electron microscopy clearly depicts better morphology of nanostructures with shell thickness of ~25nm. Room temperature magnetic measurements showed significant enhancement of magnetic anisotropy for permalloy (Ni80Fe20)-FTO over Ni-FTO core-shell nanostructures. Low temperature magnetic measurements of permalloy-FeTiO3 core-shell structure proposed strong exchange bias mechanism with magnetic coercivity below antiferromagnetic Neel temperature (TN=59K). The exchange bias is attributed to the alignment of magnetic moments in antiferromagnetic material at low temperature. Our scheme opens a path towards optimum automotive systems and wireless communications where broader bandwidths and smaller sizes are required.

Fig 1 (a) SEM micrograph for permalloy-FTO core-shell nanowires (b) TEM image of single permalloy-FTO core-shell nanowire with FTO wall thickness of 25nm (c) permalloy-FTO core-shell nanotubes, and (d) compositional analysis obtained from EDS.

Fig 2 Room temperature hysteresis loops of (a) Ni-FTO core-shell nanowires (b) Ni-FTO core-shell nanotubes (c) permalloy-FTO core-shell nanowires (d) permalloy-FTO nanotubes for magnetic field applied longitudinal and transverse to wire long axis, whereas insets represent their corresponding hysteresis loops at 5K.

[1] S. S. Ali, W. J. Li, K. Javed, D. W. Shi, S. Riaz, Y. Liu, Y. G. Zhao, G. J. Zhaib and X. F. Han, Nanoscale, 2015, 7, 13398. [2] D. W. Shi, K. Javed, S. S. Ali, J. Y. Chen, P. S. Li, Y. G. Zhao and X. F. Han, Nanoscale, 2014, 6, 7215T. [3] K. Javed, W. J. Li, S. S. Ali, D. W. Shi, U. Khan, S. Riaz and X. F. Han, Scientif Reports, 5:1820. [4] U. Khan, W. J. Li, N. Adeela, M. Irfan, K. Javed, S. Riaz and X. F. Han, Nanoscale, NR-ART-11-2015-007946.

B-64

PC-09

Fig.2 Susceptibility per Nd vs. temperature

under H=5 T for Nd3Co4Sn13. The inverse

susceptibility fitting by Curie-Weiss law

was showed in illustration.

Single crystal synthesis and physical properties of Nd3Co4Sn13

C.W. Tseng, C.N. Kuo, H.F. Liu, C.M. Wang, C.S. Lue

Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan

e-mail: pepeakf@gmail.com

Ternary stannides R-TM-Sn (R represents rare-earth element and TM represents transition metal) with the Yb3Rh4Sn13-type structure continue to attract attention in condensed matter physics due to its structural, electronic, and magnetic phenomena in the materials of this family. In this work, we report the single crystal synthesis and the physical properties of Nd3Co4Sn13. Nd3Co4Sn13 is an antiferromagnetic conpound with TN ~2.5 K and the magnetism is induced by neodymium atoms rather than cobalt [1]. To shed light on the evolution of magnetic behavior, we synthesis the single crystal by Sn self-flux method which sealed the high purity neodymium, cobalt and tin with stoichiometry in vacuumed quartz tube then heated to 1050 and quanched at 600 . The crystal photograph and powder X-ray diffraction pattern are showed in Fig.1. The temperature dependent of susceptibility of per Nd display Curie-Weiss behavior with TN~2.42 K is displayed in Fig.2. Accroding the fitting result by Curie-Weiss law, the Curie constant as 1.66 and the effective magnetic monent μeff as 3.65μB close to theoretical value indicate that the magnetism in this alloy was determined by trivalent Nd atoms[2]. Besides, the electric resistant ρ, Hall coeffecient RH and 59Co nuclear magnetic resonance (NMR) were also carried out so that the Fermi-level density of state would be disscuessed in this work.

[1] G.H. Zhong, X. W. Lei and J.G. Mao, Phys. Rev. B, 89, 094424 (2009).

[2] V. Babyuk, O. Bodak, L. Romaka, A. Tkachuk, and Yu. Gorelenko, J. Alloys Compd. 441 107

(2007)

Fig.1 Powder X-ray diffraction pattern

(blue line) and photograph of single

crystal Nd3Co4Sn13. The black line is the

contrast to database of ICSD.

B-65

PC-10

Physical properties of skutterudite-related Yb3Co3Sn13

E-mail: huan.fu.liu@gmail.com

We report single crystal growth and a systematic study of ternary stannides

Yb3Co4Sn13 including the magnetic measurements, 59Co and 119Sn nuclear magnetic

resonance (NMR) measurements. The studied sample has been grown successfully by

the Sn self-flux method. The magnetic susceptibility fit with modified Curie-Weiss

Law indicates a rather small effective moment of 0.71 μB/Yb reveling an intermediate

valence phenomenon. Moreover, a diamagnetic behavior appears below 3.8 K in the

magnetization (dc) measurement carried out with a small field of 10 Oe under

zero-field cooled and field-cooled process confirming the occurrence of

superconductivity. In addition, the resolved 59Co and 119Sn NMR spectrums both show

a slightly difference in the line shapes between 77 K and room temperature. Such an

observation could be associated to an increase of magnetic dipolar interaction in low

temperature. Also, the 59Co NMR Knight shift and spin-lattice relaxation rate 1/T1

clearly indicate that Yb3Co4Sn13 is a Pauli-type paramagnet. From the Korringa

relation (constant T1T), we thus estimated Co 3d Fermi-level density of states Nd(EF) ~

3.95 states/eV f.u. for this compound.

H. F. Liu(a)*, C. N. Kuo(a) (b), C. S. Lue(a) (b), and Y. K. Kuo(c) (a)Department of Physics, National Cheng Kung University, Tainan 70101,

Taiwan (b)Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and

Technology, Taipei 10601, Taiwan

(c)Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan

B-66

PC-11

The abnormal corrosion behavior of the (Nd,Ce)-Fe-B magnet with dual main phases in Nd2SO4 and NaCl solutions

Xiaoning Shi, Minggang Zhu, Yaping Wu, Liwei Song, and Wei Li Division of Functional Material, Central Iron & Steel Research Institute, Beijing 100081, P.R.China

Email: shixiaoning1383117@126.com Sintered NdFeB magnets are widely used in various fields in that NdFeB magnets have the most excellent

magnetic properties at room temperature. As Ce element is the most abundant rare earth element, a lot of research on the substitution of Ce for Nd has been conducted[1]. But the corrosion resistance of the Ce-riched magnet is questioned as Ce element has stronger chemical activity than Nd element. In this paper, the abnormal corrosion behavior of the (Nd,Ce)-Fe-B magnet with dual main phases in Na2SO4 and NaCl solutions has been investigated, in which (Ce3Nd17)FebalB1 and (Ce9Nd21)FebalB1 were prepared by the mixed powder sintering preparation technology. The maximum magnetic energy product (BH)max of Ce3Nd17FebalB1 and (Ce9Nd21)FebalB1 are 44.8 MGsOe and 33 MGsOe respectively, which were measured by using a NIM-2000H closed-circuit hysteresigraph and the scanning electron microscope (SEM) was used to measure the distribution of the matrix and the rare earth-riched phase. The corrosion behavior of the Ce3Nd17FebalB1 and (Ce9Nd21)FebalB1 samples have been studied in 3.5 wt.% NaCl and 0.5 mol/l Na2SO4 solutions, separately. To be specific, the polished samples were immersed in different electrolytes aqueous solution for 33 days in order to get weight loss and corrosion morphology and the polarization curves were measured with a CHI660D electrochemistry analyzer to characterize the electrochemical stability. The conclusions are as follows: a) The weight loss of (Ce3Nd17)FebalB1 is slightly bigger than that of (Ce9Nd21)FebalB1 in both 3.5 wt.% NaCl

and 0.5 mol/l Na2SO4 aqueous solutions. From the corrosion section in Na2SO4 solution, we can see that (Ce9Nd21)FebalB1 corrosion depth is slightly greater than (Ce3Nd17)FebalB1, but (Ce3Nd17)FebalB1 particles is more apt to fall off, showing that (Ce9Nd21)FebalB1 is mainly intergranular corrosion.

b) The polarization curves indicate that the free corrosion potential of (Ce3Nd17)FebalB1 and (Ce9Nd21)FebalB1 are almost equal，while the free corrosion current of (Ce9Nd21)FebalB1 is bigger than that of (Ce3Nd17)FebalB1 in both 3.5 wt.% NaCl and 0.5 mol/l Na2SO4 aqueous solutions.

c) The anode polarization resistance of (Ce3Nd17)FebalB1 is bigger than that of (Ce9Nd21)FebalB1. But the cathode polarization resistance of the former is smaller, which demonstrates that the adding content of Ce can reduce the electrochemical activity of the matrix.

d) With adding Ce element, the crystal structure of main phase is refined, which can impede the spread of corrosive pitting and intergranular corrosion in the magnets.

-1.0 -0.9 -0.8 -0.7 -0.6 -0.5

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

log

(cu

rren

t/A

)

Potential/V

Ce3Nd17FebalB1 Ce9Nd21FebalB1

a) (Ce3Nd17)FebalB1 b) (Ce9Nd21)FebalB1.

[1] M.G. Zhu, W. Li, J.D. Wang, L.Y. Zheng, Y.F. Li, K. Zhang,H.B. Feng, and T. Liu, IEEE. Trans. Magn., 50(2014), No.1, art. No.100141.

FIG. 1. The corrosion section in Na2SO4 solution of a) (Ce3Nd17)FebalB1 and b) (Ce9Nd21)FebalB1.

FIG. 2. The polarization curves in Na2SO4 solution of (Ce3Nd17)FebalB1 and (Ce9Nd21)FebalB1.

B-67

PC-12

Correlation between resistance state and saturation magnetization in (In, Co)-codoped ZnO thin film

S. S. Li(a), Y. K. Su(a,b,c) and Y. M. Hu(d)

(a) Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan (b) Institute of Microelectronics, Department of Electrical Engineering, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701,

Taiwan (c) Department of Electrical Engineering, Kun Shan University, Tainan 710, Taiwan

(d) Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan

e-mail: yksu@mail.ncku.edu.tw

The special material property in ZnO-based thin film was investigated in this study. The indium and cobalt codoped ZnO thin film was deposited by using a magnetron co-sputtering method. Bipolar resistive switching behavior and room temperature ferromagnetism have been observed in (In, Co)-codoped ZnO thin film. In particular, we measured M-H curves of the (In, Co)-codoped ZnO thin film with the bipolar resistive switching behavior in initial state, high resistance state and low resistance state. The saturation magnetization of the (In, Co)-codoped ZnO thin film with the bipolar resistive switching behavior in low resistance state was larger than that of high resistance state. In addition, much evidence has shown that the resistive switching effect and ferromagnetic property could be attributed to the intrinsic defects [1-3]. As evidenced from the photoluminescence and x-ray photoelectron spectra results indicate that there is oxygen vacancy in the (In, Co)-codoped ZnO thin film. The results clearly demonstrate the oxygen vacancy is crucial for the entire class of the ferromagnetism and bipolar resistive switching effect in (In, Co)-codoped ZnO thin film. Interestingly, the (In, Co)-codoped ZnO thin film not only shows stable bipolar resistive switching behavior, but also exhibits room temperature ferromagnetism in all of the resistance states for potential spintronic device applications in the future. [1] M. Janousch et al., Advanced Material, 19, 2332 (2007). [2] Y. M. Hu, S. S. Li and C. H. Chia, Applied Physics Letters, 98, 052503 (2011). [3] S. X. Ren et al., Applied Physics Letters, 104, 232406 (2014).

B-68

2nd August, Tuesday

B-69

BA-01

Magnetic Anisotropy Mechanisms of LTP MnBi and L10 Mn(Al,Ga) Thin Films

Takao Suzuki(a),(b),(c)

(a)Center for Materials for Information Technology (MINT), (b)Department of Electrical and Computer Engineering,

(c)Department of Metallurgical and Materials Engineering,

The University of Alabama, Tuscaloosa, AL 35487, USA

Among various high magnetic anisotropy materials, the low temperature phase (LTP) MnBi, L10

-MnAl and –MnGa exhibit high magnetic anisotropy constants (K) of the order of 107erg/cc at room

temperature [1-3]. However, the details of the magnetic anisotropy mechanism is still open to

question.

Multilayers of [Mn/(Bi, Al) x N] for MnBi and MnAl, and of [Mn/MnGa x N] for MnGa were

fabricated at an ambient temperature onto substrates of silica glass, and MgO (100), (110) and (111)

by sputter-deposition using the targets of Mn, Al, Bi and (MnGa). The multilayers thus fabricated

were annealed in vacuum at a temperature Ta from 300 ºC to 600 ºC for annealing times ta.

The LTP MnBi thin films with the preferential c-axis orientation along the film normal were

successfully fabricated onto silica glass and MgO (100) and (110) substrates with Ta=500 ~550 ºC

and ta=0.5~1 hr. It is found that the K for LTP MnBi thin films deposited onto silica glass substrates

is inversely proportional to the eighth power of Ms for T from 5 to 400K. On the other hand, that for

the films onto MgO (100) and (110) is found to be the Ms-5 [4]. (Fig.1)

Both L10-MnAl and MnGa thin films were successfully fabricated onto glass substrates. It is found

that the dependences of K on Ms for

L10-MnAl and -MnGa are found to be K ~Msn

where n= 1 and 8, respectively [5]. These

results are at variance with the theoretical

predictions for the single and two-ion models [6].

The work was partly supported by G8

project (NSF CMMI-1229049).

REFERENCES 1) T.Chen and W.E. Stutius, IEEE Trans.

Magn.,10,581,(1974). 2) H. Kono: J.Phys.Soc.Jpn.13,1444,(1958).

3) T. Bither and W.Cloud, J. Appl. Phys. 36,

1501 (1964).

4) T. Suzuki et al.: to be published in IEEE Trans MAG. (March,2016).

5) S. Zhao et al: to be published in IEEE Trans. MAG (March,2016).

6) O. N. Mryasov et al: Europhys. Lett., 69(5),805, (2005).

Figure 1. The correlation between the magnetic anisotropy constant K and saturation magnetization in LTP MnBi thin films fabricated onto fused silica glass and MgO substrates, together with the data for bulk LTP MnBi1.

B-70

BA-02

Electric field effect on magnetic properties

in metallic ultra-thin films

Daichi Chiba

Department of Applied Physics, The University of Tokyo, 113-8656, Tokyo, Japan e-mail: dchiba@ap.t.u-tokyo.ac.jp

Magnets are often needed in modern industry because they have spontaneous

magnetization. The direction of the magnetization is utilized as an information bit in magnetic recording media, and the strength of the magnetization is one factor that determines the performance of magnetic devices, e.g. a motor. If the direction or strength of the magnetization can be effectively controlled, the functions and applications of magnetic devices could be expanded, and the dissipation power of these devices will be drastically reduced. A use of not electric current but of electric field is expected to realize ultra-low power driving devices. The electric field control of the Curie temperature1), coercivity2), magnetization direction3) has been experimentally demonstrated using ferromagnetic semiconductors, in which the magnetic property is a function of a carrier concentration that can be modulated by the application of an electric field. Recently, in ferromagnetic metals (FMs), similar results have been reported at room temperature4-7). In this talk, recent experimental results on the electric field control of the ferromagnetic phase transition and magnetic moment in Co ultra-thin films are discussed6,7). In addition, electric field modifications of the magnetic moment and magnetic anisotropy in ferromagnetic Pd/MgO system are shown. 1) H. Ohno and D. Chiba et al., Nature 408, 944 (2000). 2) D. Chiba et al., Science 301, 943 (2003). 3) D. Chiba et al., Nature 455, 515 (2008). 4) M. Weisheit et al., Science 315, 349 (2007). 5) T. Maruyama et al., Nature Nanotechnol. 4, 158 (2008). 6) D. Chiba et al., Nature Mater. 10, 853 (2011). 7) K. Shimamura and D. Chiba et al., Appl. Phys. Lett. 100, 122402 (2012).

B-71

BA-03

Ultrafast magnetisation dynamics: pump-probe spectroscopy in the sub-10 fs range

D. S. Schmool(a, b), C. S. Gonçalves(b), A. S. Vieira(b), D. Navas(b), M. Miranda(c), F. Silva(b), H. Crespo(b)

(a)Laboratoire PROMES, CNRS (UPR 8521), Université de Perpignan Via Domitia,

Perpignan, France (b)Departamento de Física e Astronomia, IFIMUP, Faculdade de Ciências,

Universidade do Porto, Porto, Portugal (c)Department of Physics, Lund University, Lund, Sweden

e-mail: david.schmool@univ-perp.fr

Current time-resolution-limited dynamic measurements clearly show the necessity

for improved techniques to access magnetic processes on the sub-10-femtosecond

timescale. To access this regime, we have designed and constructed a state-of-the-art

time-resolved magneto-optic Kerr effect apparatus, based on a new dual-color scheme,

for the measurement of ultrafast demagnetisation and precessional dynamics in

magnetic materials. This system can operate well below the current temporal ranges

reported in the literature, which typically lie in the region of around 50 fs and above.

We have used a dual-colour scheme, based on ultra broadband hollow-core fibre and

chirped mirror pulse compression techniques, to obtain unprecedented sub-8-fs pump

and probe pulse durations at the sample plane [1]. We will demonstrate the application

of our system using ultrafast demagnetisation and precessional dynamics in thin

magnetic films of GdCoFe and Ni. In particular we will show that a sub-10-fs laser

pulse can be used to efficiently initiate magnetisation excitations.

[1] C. S. Gonçalves, A. S. Vieira, D. Navas, M. Miranda, F. Silva, H. Crespo and D. S. Schmool, Scientific Reports, at press (2016).

B-72

BA-04

MgO

L10-

Fe(P

t,P

d)

a =0.42 nm

a =0.38 nm

c=0

.37

nm

- 8.7 %, mismatch

MgO

L10 (001)crystal

Film thickness (nm)

0.40

0.38

0.37

a, c (nm)

0.39

1.02

0.920.94

0.96

0.98

1.00

1 10010

c/a

600

a

c

c/a

Bulk, a (A1)

A1‐FePd

A1‐FePt

A1‐FePt

A1‐FePd

a

c

c/a

Fig. 1 Dependence of lattice constants, a, c, c/a, on film thickness for A1-FePd and A1-FePt films.

Fig. 2 TEM image of L10-Fe(Pt,Pd)/MgO(001) epitaxial interface.

0.4 nm

Growth of L10 Phase in Epitaxial Magnetic Thin Films

M. Futamoto(a), M. Nakamura(a), M. Ohtake(a), T. Shimotsu(b)

(a) Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan (b) Hitachi Power Solutions, Hitachi-Naka, Ibaraki, Japan

e-mail: futamoto@elect.chuo-u.ac.jp L10 ordered materials are investigated for HAMR and MRAM applications. The

materials involve disorder (A1) to order (L10) phase transformation. Although the lattice constants, thermal expansion coefficient, and surface energy are very similar between L10-FePt and L10-FePd, the L10-variant structures are quite different. L10-(001) variant with the c-axis perpendicular to the substrate grows preferentially for FePd whereas L10-(100), (010) variants tend to mix up with the L10-(001) variant for FePt films when deposited on MgO(001) [1]. In order to study the L10-crystal growth, detailed structures are investigated for FePt, FePd, and FePt/FePd films on MgO(001) substrates prepared by employing a two-step method consisting of low temperature sputter-deposition (200 °C) followed by high-temperature annealing at 600 °C.

The relationship between lattice constants and thickness measured for FePd and FePt films with A1 structure, Fig. 1, shows that lower c/a ratios are realized in A1-FePd films. Stronger lattice strains in lateral direction are expected to promote L10-ordering with the c-axis perpendicular in FePd films. When annealed at 600 °C, only the L10-(001) crystal grew up to around 40 nm thickness for FePd films whereas L10-(100), (010) crystal with the c-axis lying in-plane started to be included in FePt films thicker than 5 nm. For FePt/FePd stacked films of 10 nm, the volume ratio of L10-crystal with the c-axis in-plane increased with increasing the FePt layer thickness. Fig. 2 shows the cross-sectional TEM image of L10-Fe(Pt,Pd) film on MgO(001). Hetero-epitaxial growth with lattice matching is realized. The present study indicates that the differences in lattice strain and the L10-crystal nucleation density are the major factors that determine the L10-variant structure in FePd and FePt epitaxial thin films. [1] M. Nakamura et al., IEICE Tech. Report, MR2015-32, pp. 57-62.

B-73

BA-05

Structure and Magnetic Properties of SmCo5, GdCo5, and YCo5 Ordered Alloy Films

Formed on Cr(100) and (211) Underlayers

Mitsuru Ohtake(a,b), Yusuke Hotta(b), Makoto Yamada(b), Ataru Suzuki(b), Masaaki Futamoto(b), Fumiyoshi Kirino(c), and Nobuyuki Inaba(d)

(a)Faculty of Engineering, Kogakuin University, Tokyo 192-0015, Japan (b)Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan

(c)Graduate School of Fine Arts, Tokyo University of the Arts, Tokyo 110-8714, Japan (d)Faculty of Engineering, Yamagata University, Yonezawa 992-8510, Japan

e-mail: mitsuru@cc.kogakuin.ac.jp

Nanocomposite magnets consisting of exchange-coupled hard and soft magnetic phases have potentials to achieve high (BH)max. In order to investigate the possibilities, it is useful to prepare samples of epitaxial thin films, since the easy magnetization axis can be controlled by the substrate orientation [1]. Bulk RCo5 (R = Sm, Gd, Y) ordered alloys show Ku greater than 107 erg/cm3 along the c-axis. In the present study, R17Co83 (at. %) films of 20 nm thickness are prepared on Cr(100) and (211) underlayers hetero-epitaxially grown on MgO substrates by MBE. The structure and the magnetic properties are investigated by RHEED, XRD, VSM, and SQUID.

Figs. 1(a) and (b) show the RHEED patterns observed for Sm-Co and Gd-Co films deposited on Cr(100) underlayers. Figs. 1(d)–(g) show the schematic diagrams of diffraction patterns simulated for R2T17, RT5, R2T7, and RT3 crystals of (11-20) orientation. The RHEED patterns are corresponding to the diffraction pattern simulated for RT5(112

_0) surface. The epitaxial orientation relationships are determined

by RHEED as RT5(11-20)[0001] (type A) and RT5(1 1_

-20)[1-100] (type B) || Cr(100)[011]. The Sm-Co and the Gd-Co films consist of two RT5(11-20) variants whose c-axes are lying in the film plane and rotated around the film normal by 90° each other. Fig. 1(c) shows the RHEED pattern observed for a Y-Co film. Diffuse diffraction pattern is overlapped with the pattern from RT5(11-20) surface. The result indicates that the Y-Co film is composed of RT5 phase mixed with amorphous phase. Fig. 1(h) shows the M-H curves of Sm-Co film. When the magnetic field along Cr[011] is decreased from +40 to 0 kOe, the magnetization of A-type variant is considered to be reversed by domain wall motion. With decreasing the field from 0 to –25 kOe, the magnetization of B-type variant seems to be reversed by magnetization rotation. The magnetic anisotropy is reflecting the magnetocrystalline anisotropy of SmCo5 crystal and the configuration of variants. The structure and the magnetic properties of R-Co films deposited on Cr(211) underlayers will be presented at the conference. [1] E. E. Fullerton et al., Appl. Phys. Lett., 69, 2438 (1996).

(a) Sm-Co (b) Gd-Co (c) Y-Co

2240

1120

2130 1230

2020 0220

_

_

_ _

_ _

2240

1120

_

_ 2240

1120

3030 0330

_

_

_

_

2240

1120

2130 1230

2020 0220

_

_

_ _

_ _

(d) R2T17 (e) RT5 (f) R2T7 (g) RT3

Nor

mal

ized

mag

neti

zati

on

–1

50

0

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(d) R2T17 (e) RT5 (f) R2T7 (g) RT3

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Fig. 1. (a)–(c) RHEED patterns observed for (a) Sm-Co, (b) Gd-Co, and (c) Y-Co films deposited on Cr(100) underlayers. (d)–(g) Schematic diagrams of RHEED patterns simulated for (11-20) surfaces with (d) R2T17-, (e) RT5-, (f) R2T7-, and (g) RT3-type structures. (h) Magnetization curves of an Sm-Co film deposited on Cr(100) underlayer.

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BA-06

Resistive switching and magnetism modulation in oxide thin films

Yuanmin Du, Chih-Huang Lai

Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C.

Resistive random access memory (RRAM) based on resistive switching effects has

attracted great interest for next-generation nonvolatile memory devices. The resistive

switching behavior is achieved by controlling the electrical field applied to a

capacitor-like metal/insulator/metal configuration, where the insulator acts as the

active layer for switching. Among the great variety of materials for resistive switching,

oxides are widely considered to be the most promising candidate. In this study, we

present a resistive switching device combining both oxide thin films and magnetic

nano-structures. The device exhibits a large and tunable resistance change with

programming voltages. Electric field controlled ferromagnetism and resistive

switching are both observed. The obtained results are discussed and finally a

mechanism has been proposed. This work is to meet the challenge of controlling

resistance and magnetism states in thin films and has potential applications in different

areas.

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Microwave-assisted magnetization reversal in perpendicular media

using obliquely applied magnetic fields

Y. Nozaki(a), S. Kasai(b)

(a) Department of Physics, Keio University, Yokohama 223-8522, Japan (b) National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan

e-mail: nozaki@phys.keio.ac.jp

Microwave-assisted magnetization reversal (MAMR) is one of the promising candidates to improve a writability of perpendicular media whose magnetic anisotropy is stronger than 1106 J/m3. Typically, a recording field is obliquely applied to the magnetization of the medium because the energy barrier height for magnetization reversal can be suppressed according to the Stoner-Wohlfarth model. However, in the MAMR, the energy barrier height is temporally varied when the trajectory of magnetization deviates from a circular orbit due to an asymmetric energy landscape. The obliquely applied magnetic field makes the energy landscape asymmetric. Thus, it is important to understand the nonlinear dynamics of magnetization excited by alternating current (ac) magnetic fields in the asymmetric energy landscape. We have experimentally investigated a critical switching condition for the MAMR in the obliquely applied magnetic field.

We can observe the MAMR from a ferromagnetic resonance (FMR) spectra which is sensitive to the effective field in the medium [1]. Now, we utilized a simple experimental setup similar to a vector network analyzer FMR spectroscopy is applicable to demonstrate the MAMR. The sample consists of an electrically shorted CPW which generates an ac field perpendicular to the center conductor. A rectangle of CoCrPt-based granular medium with a width of 200 nm and a length of 50 um was fabricated under the center conductor of the CPW. The ac magnetic field with an amplitude of 100 mT can be applied by the microwave with an amplitude of 22 dBm. An external direct current (dc) magnetic field was obliquely applied to the magnetization of the medium. The angle H between the dc magnetic field and the normal axis of the medium was ranged from 0 to 40 degree.

The coercive field Hc of the medium was minimized at 20 GHz which was similar to the FMR frequency of the medium at the coercive field. This is the clear evidence realizing the MAMR in the medium. The frequency realizing maximum reduction of Hc increased with increasing H. This is reasonable by considering the change in effective magnetic field along the magnetization direction. It is interesting that the reduction of Hc due to the assistance of ac field is suppressed by increasing H. This suggests that the optimum H for the MAMR is totally different from a conventional magnetic recording. [1] Y. Nozaki et al., J. Appl. Phys. 112, 083912 (2012).

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BB-02

Heated Dot Magnetic Recording Media – Path to 10 Tdots/in2

David S. Kuo(a), Kim Y. Lee(a), XiaoMin Yang(a), Shuaigang Xiao(a),

Yautzong Hsu(a), Zhaoning Yu(a), Michael Feldbaum(a), Tim Klemmer(a), Yukiko Kubota(a), Jan-Ulrich Thiele(a), Philip Steiner(a), Koichi Wago(a),

Stefano Dallorto(b,c), and Deirdre Olynick(b)

(a)Seagate Media Research, Fremont, California, USA (b)Molecular Foundry, Lawrence Berkeley National Lab, Berkeley, California,

USA (c)Oxford Instruments, Concord, Massachusetts, USA

e-mail: david.s.kuo@seagate.com

Continuing areal-density growth is critical for the hard disk drive industry to meet the increasing demand in data storage and to improve costs. Heat-assisted magnetic recording (HAMR) is expected to be introduced in products as perpendicular magnetic recording (PMR) approaches its limitation in areal density growth. Beyond HAMR, heated dot magnetic recording (HDMR) is considered to provide a path for further areal density growth. HDMR media is composed of lithographically defined high Ku magnetic islands or dots. HDMR Recording requires synchronously heating an individual dot to raise the dot’s temperature beyond the Curie temperature while applying a magnetic field to switch the individual dot to the desired state. HDMR media fabrication starts with a continuous FePtX film and uses advanced lithography to define magnetic islands. HDMR presents extreme challenges to lithography because of the small feature size (< 10 nm) required for high areal density. Moreover, very tight control of dot size and spacing tolerances, and the incorporation of servo features are critical to facilitate recording. Though challenging, recently the Seagate team has successfully demonstrated 5Tdpsi FtPt based HDMR media with 15K Oe of coercivity (Figure 1).

HDMR media fabrication starts with patterning of the dots in quartz wafers to form templates for nano-imprint lithography (NIL). Patterning of such templates by directed self-assembly (DSA) of block copolymers and advanced pattern doubling technique has been demonstrated as a viable lithography approach for areal density up to 5 Tdpsi. A mix-and-match DSA and conventional lithography scheme has been successfully developed for fabricating imprint templates, each comprising regular arrays of dots in data sectors, and non-periodic dot patterns in servo sectors. Templates with fully integrated servo patterns and with areal

Figure 1. 5 Tdpsi FePt islands (12.2 nm pitch) by self-assembly of PS-b-PDMS

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density of up to 2 Tdpsi (Figure 2) have been fabricated. Subsequent media fabrication involves transferring the nano features from a template into magnetic thin films by NIL and ion-beam etching (IBE). Using this approach, HDMR media with fully functional integrated servo features has been successfully fabricated on 2.5” disks with areal density of up to 2.0 Tdpsi. On a spinstand, track-following capability and basic read-write functionality of a 1.5 Tdpsi HDMR media has been demonstrated.

Although significant milestones have been achieved in HDMR technology, many challenges still remain, principally in recording margin, patterning to meet skew requirement, aspect ratio, density extensibility, dot morphology control, and magnetic material limitations. Patterned rectangular bits with lamellae-forming BCP and double patterning process is the main approach to address these concerns. Starting with imprinted resist of 48 nm pitch and utilizing BCP and pattern doubling techniques, 8 nm full-pitched lines have been demonstrated (Figure 3). These techniques form the building blocks to achieve 10Tdpsi and beyond.

Reference

1) X.-M. Yang, S. Xiao, Y. Hsu, H. Wang, J. Hwu, P. Steiner, K. Wago, K. Lee, D. Kuo, "Fabrication of servo integrated template for 1.5 Teradot/inch2 bit patterned media with block copolymer directed assembly ", J. Micro/Nanolith. MEMS MOEMS 13(3), 031307 (Jul–Sep 2014)

2) Kim Y. Lee, XiaoMin Yang, Shuaigang Xiao, Yautzong Hsu, Zhaoning Yu, Michael

Feldbaum, Philip Steiner, Koichi Wago, Ning Li, and David Kuo, “Fabrication and Characterization of Bit Patterned Media at 1.5 Tdots/in2 and Beyond”, presented at Intermag in Beijing (May 2015)

Figure 3. 8 nm pitch line by 3X direct self assembly and double patterning.

Figure 2. Servo integration by directed self-assembly and mix-and-matched lithography

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BB-03

Multiple layer magnetic recording using MAMR

Simon Greaves(a), Yasushi Kanai(b) and Hiroaki Muraoka(a)

(a)RIEC, Tohoku University, Sendai, Japan

(b)IEE, Niigata Institute of Technology, Kashiwazaki, Japan e-mail: simon@riec.tohoku.ac.jp

Microwave assisted magnetic recording (MAMR) can be used to reduce the switching field of a magnetic recording medium by tuning the high frequency (HF) field to the resonant frequency of the medium. The resonant frequency is proportional to the anisotropy field, Hk. Thus, if a recording medium contains two or more separate recording layers with different Hk it may be possible to use MAMR to selectively record on each layer [1].

Models of continuous and bit patterned recording media were used to investigate the potential of dual-layer recording. Fig. 1 shows an example of the top and bottom layer Hk values that can be switched by 28 GHz and 47 GHz HF fields as a function of write head position. For each layer there is a range of Hk values which can be switched by one HF field frequency but will not switch in the other; these ranges are indicated by the shaded areas.

Fig. 1: Switchable Hk in top and bottom layers of a dual-layer medium for HF field frequencies of 28 GHz and 47 GHz.

This talk will discuss the requirements for dual-layer recording and will present examples for continuous media and bit patterned media. Control of magnetostatic interactions between the layers and a large difference in the resonant frequencies of each layer are important design points. Approaches to analysing readback signals will also be introduced.

[1] Winkler, Appl. Phys. Lett. 94, 232501, 2009

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FePt-C granular film for heat assisted magnetic recording

Y.K. Takahashi, J. Wang, H. Pandey, A. Perumal, H. Sepehri-Amin, K. Hono

National Institute for Materials science, Tsukuba, Japan

e-mail: takahashi.yukiko@nims.go.jp

The FePt-C granular films are now considered to be most promising media for heat assisted magnetic recording (HAMR) and prototype media are currently tested in industrial laboratories. One drawback of the FePt-C system was its inability of columnar grain growth [1]. Hence, for the practical application of the FePt-C granular films as HAMR media, their microstructure must be further optimized based on the following aspects: (i) columnar growth of FePt grains with aspect ratio larger than 1.5, (ii) excellent c-axis alignment normal to the film plane and (iii) center to center distance of less than 6 nm with the grain size distribution less than 10 % [2-4].

Recently, Varaprasad et al. reported columnar growth of FePt-C grains by using a concentration graded co-sputtering method [5]. By further optimizing the deposition condition and C volume fraction, FePt-C granular films with a minimum grain size of 5.9 nm and perpendicular coercivity of 3.8 T were achieved [6]. However, a systematic approach is indispensable to understand the underlying mechanism for the columnar growth of FePt grains in FePt-C system with the size below 7 nm and least occurrence of second layer grains. In this presentation, we report systematic investigations of layer-by-layer growth mode of FePt-C nanogranular films deposited as graded structure with different C volume fraction using magnetron sputtering technique to understand the growth mechanism of columnar FePt grains without the formation of second layer, reduced grain size with narrow size distribution and the resulting magnetic properties. Reference [1] B.S.D.Ch.S. Varaprasad et al., JOM65, 853-861, 2013. [2]J. J. M. Ruigrok et al., JAP87, 5398, 2000. [3]M. Alex et al. IEEE Trans. Magn.,37, 1244, 2001. [4]D. Weller et al., IEEE Trans. Magn., 50, 3100108, 2014 [5]B.S.D.Ch.S. Varaprasad et al., IEEE Trans. Magn., 51, 3200904, 2015. [6]H. Pandey et al., IEEE Trans. Magn., vol. 99, 2015.

Microstructures and magnetic properties of typical FePt‐C granular film

B-80

BC-01

Fundamental-mode orthogonal fluxgate: A platform for versatile magnetic measurement applications

Ichiro Sasada

Dept. Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580, Japan

e-mail:sasada@ence.Kyushu-u.ac.jp

We will present the cutting edge of the magnetometry with the fundamental mode orthogonal fluxgate (FM-OFG) principle [1]. In the mode, a large dc bias current (typically 40 mA) is superposed to the ac excitation current (typically 100 kHz, 7 mA in r.m.s.) that is directory fed to a thin amorphous wire core. Due to the large dc bias current, the Barkhausen magnetic noise is well suppressed through the annihilation of domain walls at the surface area of the magnetic wire core.

FM-OFG magnetometers have already used for the magnetocardiogram (MCG) measurement [2], environmental magnetic field monitoring for the active magnetic shielding, and can be used for long-term earth’s magnetic field observation. Fig. 1 shows an MCG measurement results by 36-channel array.

Gradiometers built on FM-OFG with a slight modification from the magnetometer can be used to detect magnetic fine particles and magnetic nanoparticles under the unshielded environment [3]. Another interesting application of the gradiometer is to search residues (locally recorded magnetic moments) of the lightning strikes.

[1] Orthogonal fluxgate mechanism operated with dc biased excitation, I. Sasada, Journal of Applied Physics, vol. 91, no. 10, pp. 7789-7791 (2002) May. [2] Magnetocardiogram measured by fundamental mode orthogonal fluxgate array, Hikaru Karo and Ichiro Sasadaa, J. Appl. Phys. 117, 17B322 (2015); DOI: 10.1063/1.4918958 [3] Magnetic particle detection in unshielded environment using orthogonal fluxgate gradiometer, Ahmed L. Elrefai, Ichiro Sasada, J. Appl. Phys. 117, 17C114 (2015); DOI: 10.1063/1.4913720

Fig. 1 36 channel MCG

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BC-02

On-chip Magnetic Thin-Film Noise Suppressor to Countermeasure Digital Noise

from Switching Power Electronic Equipment

Masahiro Yamaguchi(a)(b), Satoshi Tanaka(b), Jingyan Ma(a), Yasunori Miyazawa(b), Makoto Nagata(c), Koichi Kondo(d), Yasuyuki Okiyoneda(e),

Masahiro Nishizawa(b)

(a)Dept of Electrical Engng., School of Engng., Tohoku Univ., Sendai, Miyagi, Japan (b)New Industry Creation Hatchery Center, Tohoku Univ., Sendai, Miyagi, Japan

(c)Graduate School of System Informatics, Kobe Univ., Kobe, Hyogo, Japan (d) NEC TOKIN Corporation, Sendai, Miyagi, Japan

(e) Showa Aircraft Industry Co., Ltd., Akishima, Tokyo, Japann e-mail: yamaguti@ecei.tohoku.ac.jp

Ever-expanding large-scale personal data transfer and rapidly-glowing IoT applications raise mobile communication traffic continuously. Electromangetic harmonics from fast-switching power-electronic inverter equipment, especially driven by SiC or GaN switching devices, generate unnecessary electromagnetic wave that conflicts with telecommunication frequency bands in the GHz range[1]. Accordingly it is expected to develop a new methodology to tolerate the noise suppression and signal integrity of an RF IC.

This talk studies the use of magnetic thin film inside of an IC chip, where ferromagnetic resonance losses of magnetic thin film dissipate noise power into heat. The magnetic film is implemented on to LTE-class RF IC receiver front-end circuitry. Experimental data of in-band spurious attenuation and emulation-simulation coupled diagnosis of communication performance have clarified 8 dB improvement of the LTE communication throughput. Then, base on the study on the performance of a patterned Co-Zr-Nb (Co85Zr3Nb12, 4πMs=1.05 T, anisotropy field Hk=1110 A/m and FMR frequency fr=1.2 GHz, and Co79.6Zr4.7Nb15.7, 4πMs=0.63 T, Hk=640 A/m and fr=0.8 GHz) magnetic thin-film digital noise suppressor [3], this talk suggests the design methodology of semiconductor design-compatible magnetic patterns.

The author is grateful to Profs. K. Ishiyama, H Matsuki and Y. Endo, Tohoku University for their collaboration and comments. This work was supported in part by Development of Technical Examination Services Concerning Frequency Crowding from the Ministry of Internal Affairs and Communications of Japan. [1] L. Lavagno, et al (Ed.), EDA for IC Implementation, Circuit Design , and Process Technology, CRC Press, Boca Raton, 2006. [2] M. Yamaguchi, et al, Proc. 2015 Asia-Pacific EMC Symposium (APEMC2015), 536, 2015. [3] M. Yamaguchi, et al, “Patterned Magnetic Thin-film Digital Noise Suppressor for Future Telecommunication Systems RF IC,” submitted to IEEE ICMM2016

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BC-03

Monolithic Three-Axis Fluxgate Magnetometer

Jen-Tzong Jeng(a), Chih-Cheng Lu(b), Cheng-Yao Shiue(b), Van Su Luong(a)

(a)Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

(b)Institute of Mechatronics Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

e-mail: jtjeng@kuas.edu.tw Among various kinds of three-axis magnetic field sensors, the fluxgates has been

the dominant devices in applications of navigation and motion tracking over many decades. In recent years, miniaturization of fluxgate becomes more and more important due to the requirement of electronic compass in portable electronic devices and vehicles. In this report, the promising designs of miniature three-axis fluxgate sensor are investigated. The thin-film magnetic cores for microfluxgate are fabricated onto a CMOS-MEMS chip with integrated planar coils for excitation and sensing. A high-permeability nickel-zinc ferrite core well-aligned with the planar micro-fluxgate sensor forms a flux-guide [1], of which the flux bending effect virtually depends on its geometry when the aspect ratio is close to 1. The deflection of magnetic flux allows all of the field components to be detected by the planar sensors. The combination of flux-guide and microfluxgate constitutes a monolithic vector magnetometer with the feature size of 2.5 mm. The minimum noise level is found to be 5 nT/√Hz@1 Hz. Hysteresis and non-linearity are improved with proper conditions of field modulation and synchronous detection. The non-orthogonality caused by the remaining misalignment and asymmetry can be corrected by employing a calibration process involving the voltage-to-field transfer matrix [2]. The orthogonality and linearity are demonstrated by the sinusoidal azimuth response of the vector magnetometer rotating about different axes in the geomagnetic field. The proposed designs are valuable for the future development of miniature monolithic vector magnetometer for high precision motion tracking. The similar design concepts can also be implemented in the three-axis giant magnetoresistance sensors. [1] Chih-Cheng Lu and Jeff Huang, Sensors, 15(6), 14727-14744 (2015). [2] Chia-Yi Chiang, Jen-Tzong Jeng, Bor-Lin Lai, Van Su Luong, and Chih-Cheng Lu, Journal of Applied Physics, 117(17), 17A321 (2015).

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BC-04

Tuning magnetic nanostructures of free layers for magnetoresistive sensors

Yen-Fu Liu, Xiaolu Yin, Yi Yang and Sy-Hwang Liou

Department of Physics and Astronomy and Nebraska Center for Materials and

Nanoscience,

University of Nebraska-Lincoln, Nebraska, USA 68588-0299.

The key issues for the development of magnetoresistive (MR) sensors are to reduce

sources of noises, to increase the signal, and to understand the involved fundamental

limitations. The high sensitive MR sensors result from the optimization of magnetic

tunnel junction (MTJ) parameters, such as tunneling magnetoresistance ratio (TMR),

coercivity (Hc), exchange coupling field (He), domain structures, and noise properties

as well as the external magnetic flux concentrators. All these parameters are sensitively

controlled by the magnetic nanostructures, which can be tuned by varying junction free

layer nanostructures, geometry, and magnetic annealing process etc. In this talk, we

discuss the tuning magnetic nanostructures of free layer for magnetoresistive sensors.

We show an optimized magnetic sensor with a sensitivity as high as 5,146 %/mT. This

sensitivity is currently the highest among all MR-type sensors that have been reported.

The estimated noise of our magnetoresistive sensor is 47 pT/Hz1/2 at 1 Hz. This

magnetoresistance sensor dissipates only 100 μW of power while operating under an

applied voltage of 1 V at room temperature.

E-mail:

Yen-Fu Liu, liuyenfu@gmail.com

Xiaolu Yin, yinxiaolu@huskers.unl.edu

Yi Yang, youngy1991@gmail.com

Corresponding Author

Sy-Hwang Liou, sliou@unl.edu

B-84

PD-01

A first-principles study on the magnetic properties of Sc,

V, Cr and Mn-doped monolayer TiS3

Huiling Zheng and Yu Yan

Department of Physics, Jilin University, Changchun 130012, China

The geometrical structure, electronic structure and magnetic properties of Sc, V, Cr, Mn-doped monolayer TiS3 are investigated using first-principles calculations in the framework of density functional theory. The results show that the substitutional doping of Sc, V, Cr and Mn atoms in monolayer TiS3 are possible under Ti poor condition and all of the doped systems are stable at room temperature. Furthermore, it is found that the ground state of V, Cr and Mn doped systems are magnetic and the magnetic moments induced by dopant mainly come from the 3d states of the dopants with a partial contribution from 3p states of their neighboring S atoms. In particular, the magnetic coupling between the moments induced by two V and Mn is long-range ferromagnetic and the coupling can be attributed to the hybridization interaction involving polarized electrons, whereas the coupling between the moments induced by two Cr is anti-ferromagnetic. The last result suggests that the substitutional doping of V and Mn atoms can induce the room temperature ferromagnetism in monolayer TiS3.

Keywords: Monolayer TiS3, Magnetism, First-principles, Doping

B-85

PD-02

Magnetic Properties of MnCo1-xFexGe (0 ≤ x ≤ 0.12)

M. Onoue(a), K. Ozono(a), Y. Mitsui(a), M. Hiroi(a), R. Y. Umetsu(b), K. Takahashi(b), Y. Uwatoko(c), K. Koyama(a)

(a)Graduate School of Sci. & Eng., Kagoshima Univ., Kagoshima, 890-0065, Japan

(b)Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan (c)Institute for Solid State Physics, The Univ. of Tokyo, Kashiwa, 277-8581, Japan

e-mail: m-onoue@gm.kagoshima-u.ac.jp Recently, it was found that ferromagnetic MnCo0.92Fe0.08Ge showed first-order

transition between the paramagnetic and ferromagnetic state with a thermal hysteresis of 24 K, which was accompanied by the martensitic transformation from the hexagonal Ni2In-type structure to the orthorhombic TiNiSi-type structure in the vicinity of 275K [1]. The compound showed both metamagnetic transition and magnetic field-induced martensitic transformation [1]. In this study, we performed magnetic and Mössbauer effect measurements of MnCo1-xFexGe (0 ≤ x ≤ 0.12) to clarify its fundamental properties on magnetism.

Magnetization M measurements were performed using a SQUID magnetometer and VSM at T = 10-570 K. The measurements of 57Fe Mössbauer effects were carried out at 10-300 K by transmission method.

Fig. 1 shows the M-T curves of MnCo0.92Fe0.08Ge under a magnetic fields of 0.05 T and 5 T. The first-order magnetic transitions are observed between 250K and 300K. The magnetization is 111 Am2kg-1 (3.7 　B/f.u.) at 10K, which is consistent with the results of neutron diffraction experiments [2].

Fig. 2 shows the Mössbauer spectrum together with a fitted curve of MnCo0.88Fe0.12Ge at 290 K. Assuming that Fe atoms occupies only the Co-site, the isomer shift (IS) and the quadrupole splitting (QS) are estimated to be -0.31 mm/s and 0.80 mm/s, respectively, for x = 0.12. Obatined results suggested that Fe2+ ions with S = 0 state (low spin state) exist in MnCo1-xFexGe compound. [1] K. Ozono, et al., Mater. Trans., 57, 316, (2016). [2] S Niziol, et al., J. Magn. Magn. Mater., 27, 281 (1982).

Fig.1. M-T curves of MnCo0.92Fe0.08Ge under a magnetic fields of 0.05 T and 5 T.

Fig.2. Mössbauer spectrum of MnCo0.88Fe0.12Ge at 290 K.

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PD-03

Magnetic and Structural Properties of Mn1.9Fe0.1Sb0.9Sn0.1 under Magnetic Fields

A. N. Nwodo(a), R. Kobayashi(a), T. Wakamori(a), Y. Mitsui(a), M. Hiroi(a), K. Takahashi(b), Y. Uwatoko(c), Keiichi Koyama(a)

(a)Graduate School of Sci. & Eng., Kagoshima Univ., Kagoshima, 890-0065, Japan

(b)Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan (c)Institute for Solid State Physics, The Univ. of Tokyo, Kashiwa, 277-8581, Japan

e-mail: beautyadline@yahoo.com

The compound Mn2Sb has interesting magnetic properties and crystallizes in Cu2Sb

type tetragonal structure (space group: P4/nmm) and orders ferrimagnetically (FRI)

below TC ~ 550 K [1]. This compound has received a growing interest due to the effect

of magnetic field along with the tunability of the transition temperature up to and above

room temperature [1]. It has been reported that the Mn2Sb-based pseudo-binary

compounds showed first-order transition between the FRI and antiferromagnetic

(AFM) state [1]. In this work, we found that Mn2Sb-based pseudo-binary compound,

Mn1.9Fe0.1Sb0.9Sn0.1, shows first-order transition between the FRI and paramagnetic

(PM) state for the first time. The

magnetization and X-ray diffraction (XRD)

measurements were performed in 10 ≤ T ≤ 360

K and in magnetic fields B up to 5 T to clarify

the magnetic and the structural properties of

the compound.

Fig. 1 shows the temperature dependence of

the magnetization of Mn1.9Fe0.1Sb0.9Sn0.1 in 0.1

T and 5 T. As seen in the figure, for B = 0.1 T,

Mn1.9Fe0.1Sb0.9Sn0.1 undergoes a first-order

magnetic transition from a FRI to a PM phase

with thermal hysteresis at 310 K. By applying

magnetic field of 1 T, the transition vanishes.

The low-field magnetic data also showed an

anomaly at 100 K and 200K, indicating a spin

reorientation.

[1] O. Beckman and L. Lundgren, Handbook of Magnetic Materials vol. 6, ed. by K. H.

J. Buschow, (Amsterdam, Elsevier, 1991) pp. 181-287.

Fig.1 Temperature dependence of

the magnetization of

Mn1.9Fe0.1Sb0.9Sn0.1 under 0.1 T and

1T.

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PD-04

Magnetic Fields Effect on Phase Formation of Ferromagnetic MnBi Synthesized by Reactive Sintering

Daiki Miyazaki(a), Yoshifuru Mitsui(a), Kohki Takahashi(b), Keiichi Koyama(a)

(a)Graduate School of Science and Engineering, Kagoshima University,890-8865,

Kagoshima, Japan (b) Institute for Materials Research, Tohoku University, 980-8566, Sendai, Japan

e-mail: k1841268@kadai.jp

Magnetic field processing has been studied actively in the world. Recently, it was reported that the fraction of ferromagnetic MnBi was increased by applying magnetic fields during solid-state sintering process [1]. However, the origin of magnetic field effect on the solid-state sintering process has not been investigated in detail. In this study, for investigating the origin of the magnetic field effect, we performed microstructural analysis for MnBi synthesized by reaction sintering.

The pellet-shaped sample of Bi-Mn alloy was prepared by compacting the mixed powder Mn (< 150 μm) and Bi (< 150 μm). After that, in-field reactive sintering heat treatment was carried out for the obtained pellet. The microstructure of the sample was observed and analyzed by scanning electron microscopy (SEM) and electron probe micro analyzer (EPMA). Fig. 1 shows the SEM image and the EPMA line profiles of Bi and Mn for the sample sintered for 24 hours in a zero field. Black and white areas indicate the existence of Mn and Bi phase, respectively. Gray area indicates the ferromagnetic MnBi phase. The area of MnBi phase was estimated by both of SEM image and the EPMA line profiles. Obtained results indicate that peritectic reaction in Bi-Mn is promoted by magnetic fields. In the presentation, we will discuss magnetic fields effect on the reactive sintering of MnBi on the basis of reacted fractions. [1] Y. Mitsui, et al., J. Alloy. Compd. 615 (2014) 131-134.

Fig. 1. SEM image and the distribution of the

elements for the sample sintered in a zero

fields.

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PD-05

Pressure Effect on Weak Itinerant Electron Ferromagnet

Ni3Al

S. Yoshinaga(a), T. Kanomata(b), Y. Mitsui(a), K. Koyama(a)

(a) Graduate School of Science and Engineering, Kagoshima University, Kagoshima

890-0065, Japan

(b)Research institute for Engineering and Technology, Tohoku-Gakuin University, Tagajyo 985-8537, Japan

e-mail: k5997477@kadai.jp

Intermetallic compound Ni3Al with the L12-type structure is a weak itinerant

electron ferromagnet (WIFE) with a Curie temperature TC of 45 K. For WIFE,

Takahashi proposed a spin fluctuation theory, in which quantum spin fluctuations

(zero-point spin fluctuations) were considered [1, 2]. In this study, we performed

magnetization measurements of Ni3Al under high pressures up to 1.2 GPa. The

obtained data were analyzed based on Takahashi’s theory [1, 2]. In this paper, we

discuss the pressure dependence of the characteristic parameters of Takahashi’s spin

fluctuation theory.

Figure 1 shows the pressure dependence of the

parameters characterized by the energy width of the

dynamical spin fluctuation spectrum T0 and the

dispersion of the static magnetic susceptibility in the

wave vector space TA, respectively. As shown in Fig.

1, it is found that T0 and TA increase with increasing

pressure.

[1] Y. Takahashi, J. Phys.: Condens. Matter, 13, 6323 (2001) [2] Y. Takahashi and T. Kanomata, Mater. Trans., 47, 460 (2006)

Fig. 1. The pressure

dependence of spin fluctuation

parameters, T0 and TA

B-89

PD-06

Magnetic Field-Induced L10-Ferromagnetic MnAl

R. Kobayashi(a), Y. Mitsui (a), R. Y. Umetsu(b), K. Takahashi(b), M. Mizuguchi(b), K. Koyama(a),

(a)Graduate School of Science and Engineering, Kagoshima University, 890-0065,

Kagoshima Japan (b)Institute for Materials Research, Tohoku University, 980-8577,Sendai, Japan

* R. Kobayashi: k3579242@kadai.jp L10-MnAl (-phase) is one of the Mn-based ferromagnetic alloys with high uniaxial magnetic anisotropy. As -phase is not equilibrium state, synthesis of -phase is accompanied by the appearance of non-ferromagnetic equilibrium phases. On the other hand, ferromagnetic phase is stabilized under the magnetic fields by the gain of Zeeman energy. The enhancement of ferromagnetic property was realized by in-field annealing for MnAl film [1]. However, there is no report that synthesis of bulk phase MnAl succeeds by using high magnetic fields. In this study, for obtaining the high fraction of phase, in-field synthesis for MnAl alloys were performed under high magnetic fields up to 15 T. The cast rod-shaped Al-55at%Mn was obtained by induction melting. Then, the sample was cut into disks. The disk-shaped sample was sealed in an evacuated quartz tube and annealed at 1373 K for 1 day as the solution treatment. After that, the sample in the quartz tube was quenched into ice water. All samples were confirmed to be -phase with hcp structure by X-ray diffraction (XRD) measurements. In-field heat-treatments of the -phase samples were performed at 573 K in a zero field, a magnetic field of 10 and15 T. Fig. 1 shows the magnetization at 1.5 T in the function of annealing time t. For t > 48 h, the magnetization was clearly enhanced by in-field heat treatment, which was consistent with the results of XRD measurements. The results clearly show that the in-field heat treatment enhanced the crystallization of ferromagnetic -phase MnAl. References:

[1] G.A.Fischer,et al.,J.Magn.Magn.Mater. 213 (2000) 335.

Fig.1. The magnetization of Mn-Al

alloys in the function of annealing

time.

B-90

PD-07

Magnetic Field Effects on the Morphology of Bi-Mn System

A. Takaki(a), Y. Mitsui(a), D. Miyazaki(a), R. Y. Umetsu(b), K. Takahashi(b), K. Koyama(a)

(a)Graduate School of Science and Engineering, Kagoshima University,

Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

e-mail: k8132539@kadai.jp

In-field heat treatment for Bi-Mn alloys has been performed so far [1, 2]. The ferromagnetic MnBi grain elongated and aligned along the magnetic field direction in the Bi-rich matrix [1]. On the other hand, the magnetic orientation of the reacted MnBi phase is difficult during the solid-phase reaction. Thus, combining the liquid- and solid-phases reactions under magnetic fields will be a new method to control the morphology of the magnetic materials. In this study, focusing on the control of alignment of grain, elongation, and crystal orientation promoted by magnetic field, microscopic observation for Bi-Mn alloys synthesized by in-field solid-state reaction were performed. Fig.1 shows the powder X-ray diffraction patterns for the Bi-Mn samples. As seen in Fig. 1 (b), the diffraction peaks of ferromagnetic MnBi compound are clearly observed for only the in-field reacted sample (15 T 250 OC 24 h), resulting the enhancement of the reaction and crystal orientation. In the presentation, we will also show the SEM image of the samples and discuss the magnetic field effect on the grain size, shape of grain, and crystal orientation. [1] C. Lou et al., J. Alloy. Compd., 505 (2010) 96. [2] Y. Mitsui et al. J. Alloy. Compd., 615 (2014) 131.

Fig.1. Powder XRD pattern of the

Bi-20at.%Mn.

B-91

PD-08

Nonlinear Temperature Characteristics in Magnetic Nanoparticles due to Hysteresis-Generated Heat

J. W. Yu(a), B. C. Chen (b), C. Y. Ho (a), , M. Y. Wen(c)

(a) Department of Mechanical Engineering, Hwa Hsia University of Technology, Taipei 235, Taiwan

(b) Department of Chinese medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi 622, Taiwan

(c) Department of Mechanical Engineering, Cheng Shiu University, Kaohsiung 833, Taiwan

e-mail: hcy2182@yahoo.com.tw

Hysteresis-generated heat induces the temperature rise in magnetic nanoparticles subject to external alternative magnetic field. The heat generation due to hysteresis gives the nonlinear thermal field which affects the temperature stability and results in oscillation. Magnetic nanoparticles with temperatures under control are preferred for many applications. The temperature instability and difficulty of control are possibly attributed to the nonlinear thermal characteristics of magnetic nanoparticles due to hysteresis-generated heat contributes. Therefore this paper studies the nonlinear temperature characteristics of magnetic nanoparticles due to hysteresis-generated heat. The criterion of instability is presented and the effects of parameters on the nonlinear temperature characteristics are discussed.

0 100 200 300r (from exterior of nanoparticle)

0

2

4

6

8

T

0 2 4 6 8

T

-0.4

-0.2

0

0.2

0.4

T'

Figure 1 temperature distribution and phase space

Figure 1 indicates the temperature oscillates along the radial direction. For some parameter set, the oscillation of the temperature increases with the radial distance and divergence occurs at the surface of nanoparticle. The phase space is also shown in this figure. The amplitude magnitude and central location of oscillation are revealed in the phase space.

B-92

PE-01

Spin polarization and magnetization of Heusler alloys Co2TiGa1−xSnx (x = 1.0, 0.5)

R. Ooka(a), Y. Sukino(a), Y. Fujimoto(a), I. Shigeta(a), R. Y. Umetsu(b),

A. Nomura(b), T. Yamauchi(c), T. Kanomata(d), K. Yubuta(c), M. Hiroi(a)

(a)Grad. Sch. of Sci. and Eng., Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan (c)Institute for Solid State Physics, University of Tokyo, Chiba 277-8581, Japan

(d) Grad. Sch. of Eng., Tohoku Gakuin University, Tagajo 890-8511, Japan e-mail: op11rz.g@gmail.com

Spintronic devices, such as magnetic random access memory (MRAM), are built

from materials with high spin polarization. Half-metals which have only one spin band at the Fermi level are necessary to improve the performance of the spintronic devices. Co-based Heusler alloys are predicted relatively high Curie temperature and high spin polarization from the first-principle band calculations. We therefore focus on the spin polarization and magnetization of Co-based Heusler alloys Co2TiGa1−xSnx.

Co-based Heusler alloys Co2TiSn and Co2TiGa0.5Sn0.5 were prepared by arc melting high-purity elements in an Ar atmosphere. Magnetization was measured by using a commercial SQUID magnetometer. We fabricated planar-type junctions by depositing a superconducting Pb film on the polished surface of Heusler alloys Co2TiGa1−xSnx. Spin polarization of Co2TiGa1−xSnx was determined by the Andreev reflection method using Co2TiGa1−xSnx/Pb junctions.

The spontaneous magnetization Ms was estimated to be 1.98 μB/f.u. for Co2TiSn and 1.45 μB/f.u. for Co2TiGa0.5Sn0.5, respectively. These values are close to Slater-Pauling behavior. The normalized differential conductance G/GN was therefore analyzed by the modified Blonder-Tinkham-Klapwijk (BTK) theory [1]. Figure 1 shows a representative fitting result of normalized differential conductance by the BTK theory, where the fitting parameters are the spin polarization P, the superconducting gap Δ, the spectral broadening parameter ω and the dimensionless barrier strength Z. The intrinsic value of P can be estimated by extrapolation to Z = 0. The intrinsic P values are relatively high of 58.4 ± 2.3% for Co2TiSn and 58.0 ± 3.2% for Co2TiGa0.5Sn0.5, respectively. [1] G. J. Strijkers, Y. Ji, F. Y. Yang, C. L. Chien and J. M. Byers, Phys. Rev. B. 63, 104510 (2001).

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

-15 -10 -5 0 5 10 15

G (V)/ GN

V (mV)

Experimental dataFitting resultCo2TiSn

P = 59.2%? = 0.89 meV? = 0.51 meVZ = 0.00?2 = 4.19 10-6

Fig. 1 Fitting result of normalized

differential conductance at 4.2 K by

B-93

PE-02

Nano-oxide layer induced magnetic property of

IrMn-based spin-valve field sensors

Manish Kumar Srivastava(a), Kuo-Feng Huang(b), Hsin-Hung Huang(c), Rex

Weng(c), W. F. Pong(a) and Chih-Huang Lai(b)

(a)Department of Physics, Tamkang University, Tamsui, Taiwan (b)Department of Materials Science and Engineering, NTHU, Hsinchu, Taiwan

(c)Sensortek Technology Corporation, Hsinchu County 302, Taiwan

e-mail: manish2007bhu@gmail.com

An orthogonal magnetization configuration between free (FL) and pinned layer (PL) is

required in GMR field sensor. Typically, shape anisotropy for FL and exchange anisotropy

for PL are used to achieve such configuration in patterned devices. In this study, biquadratic

coupling (BC) is achieved through the insertion of a nano-oxide layer (NOL) in sheet film

structure at specific position. A multilayer with the layer sequence of

Si/Ta/Pt/IrMn/Co/FeOx/Co/Cu/Co/NiFe/Ta is fabricated. Fe based NOL is formed by

exposing Fe layer to oxygen plasma for 15 seconds.

Magnetization (M-H) and Angular-MR measurements have been done to study the

effect of NOL in sheet films and patterned devices, respectively. Fig.1 shows the M-H loops

of the sheet film, which clearly shows the presence of exchange bias (0o loop) and BC

between Co layers across the NOL layer (90o loop). Magnetization directions are shown in the

inset of Fig.1. 0o designates the measurement along the annealing direction. For field sensor

applications, we patterned the films into rectangular GMR wires (100um×5um) followed by

the field annealing along a tricky direction (inset of Fig.2) to set a certain angle between FL

and magnetization direction of Co layer lying on the top of NOL, called reference layer (RL).

To learn how the patterning affects the FL, i.e., the angle between FL and RL, we measured

angle-dependent resistance (R) (see Fig.2). Measurement procedures can be explained during

presentation. Fig.2 shows that, R increases as the measuring field

approaches 90o, indicating larger angle

between FL and RL. The Rmin occurs at

225o, suggesting the angle between FL and

RL is 45o. This result clearly demonstrates

that the BC coupling is maintained between

Co layers across the NOL even after

patterning.

Fig.1:M-H characteristics, Fig.2: Angular-MR measurement

-3000 -2000 -1000 0 1000 2000 3000

-1.0

-0.5

0.0

0.5

1.0

M/M

s

H (Oe)

0 deg 90 deg

(1)

0 100 200 300 400 500 600 700 800

505.6

505.8

506.0

506.2

506.4

Res

ista

nce

(O

hm

)

Angle (Theta)

(2)

B-94

PE-03

Separation of spin Seebeck effect and anomalous Nernst effect

H. Wu, C. H. Wan, Z. H. Yuan, X. Zhang, and X. F. Han*

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

e-mail: xfhan@iphy. ac.cn

Spin Seebeck effect (SSE) in ferromagnetic insulators can generate a pure spin current by the thermal gradient, which attracted a great deal of attention in spintronics research. Recent works focused on using the inverse spin Hall effect (ISHE) in ferromagnetic metals to detect the spin current generated by longitudinal SSE [1]. However, in ferromagnetic metals the thermal gradient will also induce the anomalous Nernst effect (ANE) [2], so the separation of longitudinal SSE and ANE in ferromagnetic metals is in great demand. In this works, we provide the exchange bias structure (NiFe/IrMn) to detect the spin current. The exchange bias structure provides a shift field to NiFe, which can separate the magnetization of NiFe from that of YIG in M-H loops. As a result, the ISHE related to magnetization of YIG and the ANE related to the magnetization of NiFe can be separated as well. The ISHE voltage around 0 Oe is from the SSE in YIG, and the ANE voltage around 180 Oe is from the NiFe itself. Furthermore, the signs of ISHE and ANE are the same in NiFe. When we inserted an insulator layer MgO between YIG and NiFe to block the spin current, the ISHE voltage vanishes and the ANE voltage still exists, which confirms the ISHE signal does not come from NiFe itself. By linear fitting the VISHE/R-ΔT curves of NiFe and Pt, we calculated the relative spin Hall angle θ(NiFe)/θ(Pt)=0.87. Except for the strong spin-orbit coupling (SOC), the ferromagnetic order also plays an important role in this large spin Hall angle of NiFe. This work indicates that ferromagnetic metals can also be used to detect the spin current in spintronics devices. [1] B. F. Miao, S. Y. Huang, D. Qu,

and C. L. Chien, Phys. Rev. Lett. 111, 066602 (2013).

[2] H. Wu, C. H. Wan, Z. H. Yuan, X. Zhang, J. Jiang, Q. T. Zhang, Z. C. Wen, and X. F. Han, Phys. Rev. B 92, 054404 (2015).

Fig. 1 shows the spin dependent

thermal voltage measurement.

B-95

PE-04

Magnetic domain wall motion in Co/Ni nanowires induced by a sloped electric field

K. Yamada, S. Murayama, and Y. Nakatani

Graduate school of Informatics and Engineering,

University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan e-mail: nakatani@cs.uec.ac.jp

Recently, the domain wall (DW) motion device has attracted a great deal of attention, because it will be a candidate for a nonvolatile information storage, which has a potential for reducing consumption power [1]. In this device, the DW motion is controlled by the magnetic field or the current. However, it is required to reduce the consumption power. In recent years, as a new method for reducing the power, the electric field-driven DW motion method has been proposed [2,3]. In these studies, they used not only a electric field, but also a magnetic field for DW motion to increase the driving force. In this study, we perform the micromagnetic simulations, and investigate the DW motion by using a sloped-electric-field (SEF). Since the anisotropy field in the magnetic nanowire can be changed at each position in this approach [4], it lead to change the DW energy at each position, and accordingly, the DW moves only by this electric field [5].

The change in the DW velocity with 　Ku is shown in the red points in Fig. 1 [the reduction rate of the anisotropy by the SEF was defined by 　Ku]. The DW velocity increases substantially in proportion with　　Ku up to 　Ku ＝1.4 Gerg/cm4, then the DW velocity decreases gradually because of the breakdown. The maximum DW velocity is 1005 cm/s at 　Ku ＝1.4 Gerg/cm4. In the case of the small reduction rate up to 　Ku ＝1.4 Gerg/cm4, the DW motion has steady-state motion, whereas it has precessional motion over 　Ku ＝1.4 Gerg/cm4. This phenomenon is the same as the Walker breakdown.

We derived the analytical equation of the DW velocity from the change in the DW energy caused by the SEF (the black crosses in Fig. 1). This analysis of the DW velocity is in good agreement with the simulated results, and the effective magnetic field ( ) caused by the SEF-driven DW motion can be quantitatively estimated using the analytical equations. [1] S. S. P. Parkin, et. al., Science 320, 190 (2008). [2] A. J. schellekens, et. al., Nat. Commun. 3, 848 (2011).

[3] D. Chiba, et. al., Nat. Commun. 3, 888 (2012). [4] M. Weisheit, et. al., Science 315, 349 (2007).

[5] T. Shiratori, et, al., J. Magn. Soc. Jpn 22, 4750 (1998).

Fig. 1 Change in the DW velocity withthe reduction rate of the anisotropy.

B-96

PE-05

Fig. 1: DW velocity for different values of D. The results of the 2D (marks) and 1D (dotted line) calculations for the wire widths (a) w = 50, (b) 100, (c) 200, (d) 300, (e) 400, and (f) 500 nm.

Excitation of magnetic domain wall velocity in (Co/Ni) nanowires induced by blocking the motion of

vertical Bloch lines

K. Yamada, and Y. Nakatani Graduate school of Informatics and Engineering,

University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan e-mail: nakatani@cs.uec.ac.jp

The Dzyaloshinskii-Moriya interaction (DMI) has been a great attention in the magnetic domain wall (DW) motion[1-4]. It has been reported by the theoretical analysis that the DMI produces an effective chiral field that stabilizes Néel type walls, leading to efficient coherent motion (the steady motion) much faster than the DW velocity of several hundred at the Walker field (Hw) [1,2]. In these reports, they have studied the DW motion around the Hw, however they have not discussed the DW motion in a high field region in which it is moved with the precessional motion. In the region, the DW velocity is affected by fluctuations of DW shape [5], and the vertical Bloch lines (VBLs) are nucleated and moved on the DW. In this report, we perform micromagnetic simulations and investigate the field-driven DW motion in a (Co/Ni) nanowire under the DMI, in particularly, in the high field region where is much higher than the Hw.

The two-dimensional (2D) micromagnetic model is used in simulations. Typical material parameters for perpendicular magnetized Co/Ni multilayer film are used [6]. Figures 1(a–f) show the effect of Hext on the DW velocity for various values of D and various wire widths. Above Hw, at D > 0.4 erg/cm2, the DW velocity decreases first with increasing Hext and thereafter increases. This re-increment of the DW velocity occurs twice more as the external field increases beyond Hw. The fields for velocity re-increments vary according to the values of D and w. This effect is caused by the change in the DW structure with the DW motion induced by the blocking of the motion of VBLs at the bending region of the DW [7].

[1] A. Thiaville, et al., Europhys. Lett. 100, 57002 (2012). [2] O. Boulle, et al., Phys. Rev. Lett. 111, 217203 (2013). [3] S. Emori, et al., Nat. Mater. 12, 611 (2013). [4] K.-S. Ryu, et al., Nat. Nanotechnol. 8, 527 (2013). [5] K.Yamada, et al., Appl. Phys. Express. 4, 113001 (2011). [6] R. Hiramatsu, et al., Jpn. J. Appl. Phys. 53, 108001 (2014). [7] K.Yamada, et al., Appl. Phys. Express. 8, 093004 (2015).

B-97

PE-06

4 4.5 5 5.5

Ku(Merg/cm3)

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6 1.8

2

D(e

rg/c

m2 )

0 20 40 60 80 100 120140

Rs

(nm

)

in-p

lan

e m

agn

etiz

atio

n

uniform state

multidomain state

Examination of stability of skyrmions structure in Co/Ni multilayer films

S. Hozumi, K. Yamada, and Y. Nakatani Graduate school of Informatics and Engineering,

University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan e-mail: nakatani@cs.uec.ac.jp

Recently, the characteristic twisted magnetization structure called magnetic

skyrmions is expected to be a next-generation non-volatile memory and logic device[1-4]. It has been observed in a ferromagnetic ultrathin film with perpendicular anisotropy sandwiched with nonmagnetic layers, where the interface effect originated from the Dzyaloshinskii–Moriya interaction (DMI) is acted. In order to use skyrmions as a memory, the recorded information (= skyrmion structure) has to retain in the device. Therefore, it is necessary to investigate the stability of the skyrmion structure . In this study, we focus on the ferromagnetic ultrathin film of the Co/Ni multilayer with the DMI, and investigate the stability of the skyrmion structure using the micromagnetic simulations. Material parameters of Co/Ni multilayers used in the simulation are the saturation magnetization Ms = 837 emu/cm3, exchange stiffness constant A = 1.0 erg/cm, uniaxial anisotropy constant Ku = 4.0 ~ 6.0 Merg/cm3, strength of DMI constant D = 0.0 ~ 2.0 erg/cm2 [5]. Figure 1 shows the diagram of the skyrmion structure with the diameter of the skyrmion by changing Ku and D. In the case of Ku 4.3 Merg/cm3, the skyrmion structure does not present because it is an in-plane magnetization. In the case of Ku = 5 Merg/cm3, the skyrmion structure is a multi-domain state in the conditions of D 1.1 erg/cm2, and it annihilates in D 0.4 erg/cm2. In 0.5 D 1.0 erg/cm2, the skyrmion structure is presented in the stable, and the diameter is increased with increasing the D. In order to be make the skyrmion structure in the stable in the condition of Ku 4.4 Merg/cm3, it is necessary to increase both Ku and D.

[1] T. H. R. Skyme, Proc. Roy. Soc. Lond. A 31, 556 (1962). [2] X. Z. Yu, et al., Nature. 465, 901-904 (2010).

[3] J. Iwasaki, et al, Nat. Nanotechnol. 8, 742-747 (2013). [4] S. Rohart, et al., Phys. Rev. B 88, 184422 (2013). [5] R. Hiramatsu, et al, Jpn. J. Appl. Phys. 53, 108001 (2014).

Fig. 1 Diagram of skyrmion structure with the diameter (Rs) by changing Ku and D.

B-98

PE-07

Polarization-Mediated Thermal Stability of CoFeB/BiFeO3 Heterointerface

Qintong Zhang(a), Lu You(b), Xi Shen(a), Caihua Wan(a), Richeng Yu(a), Junling Wang(b), and Xiufeng Han(a)*

(a)Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,

Chinese Academy of Sciences, Beijing 100190 (b)School of Materials Science and Engineering, Nanyang Technological University,

639798, Singapore e-mail: xfhan@iphy.ac.cn

Heterointerface comprising ferromagnetic metals and ferroelectric/multiferroic

oxides is a hopeful candidate for the next-generation magnetoelectric memories, in which magnetic state can be modulated electrically via strain-/spin interfacial couplings [1,2]. To obtain high tunneling magnetoresistance ratio, annealing process is indispensible for magnetic tunneling junction devices. However, this annealing process will inevitably promote the chemical reaction between oxygen and metal atoms, further destroying the magnetic interfacial coupling of a ferromagnetic/multiferroic heterointerface and eventually leading to the failure of devices. Therefore, the thermal stability of the ferromagnetic/multiferroic interface is one core problem to develop magnetoelectric memories.

In this study, we have investigated the thermal stability of GMR devices grown on ferroelectric BiFeO3 films. Oxygen vacancies asymmetric distribution induced by polarization is the key to the change thermal stability of the metal/oxide heterointerface. Through polarization engineering, the thermal stability of the interface between BFO and CoFeB can be improved. The oxidation reaction around the interface is confirmed by combining STEM and EELS with macroscopic magnetic characterizations.

[1] J. T. Heron et.al.. Nature 516 (2014) 370. [2] S. Dunn, P. M. Jones, D. E. Gallardo, J. AM. CHEM. SOC. 129 (2007) 8724. [3] Q. T. Zhang and X. F. Han et.al., Adv. Mater. 27 (2015) 6934

Annealing temperature (TA) dependence of normalized GMR

B-99

PE-08

Spin Current Tunneling through an Al2O3 Oxidation Barrier Investigated by Spin Pumping Eect

Kuan-Chia Chiu(a), Wen-Che Chang(a), Jhen-Yong Hong(a), M. Sanjoy Singh(a),

Gaun-Yu Luo(b), Jauyin-Grace Lin(b) and Minn-Tsong Lin(a),(c),(d)*

(a) Department of Physics, National Taiwan University, Taipei 106, Taiwan (b)Center for Condensed Matter Sciences, Taipei 106, Taiwan

(c)Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (d) Research Center for Applied Science, Academia Sinica, Taipei 106, Taiwan

* E-mail: mtlin@phys.ntu.edu.tw

The detection of spin current tunneling is investigated by a technique of

ferromagnetic resonance (FMR) with Inverse Spin Hall voltage (VISH) measurement in

Pt/Al2O3/Py trilayer system. It is seen that the value of VISH is exponentially decreasing

with the thickness of oxide barrier increasing. Furthermore, FMR and VISH are

measured with the sample rotating out of plane while the magnetic field direction is

fixed. Although the angular dependence of VISH in Pt/Al2O3/Py system is asymmetric,

the resonance field is quite symmetric with respect to angle. Current vs. voltage (I-V)

relation is measured in Pt/Al2O3/Py with current perpendicular to the film surface and

found to be non-linear. The combined results of FMR, VISH and non-linear I-V

characteristic suggest the spin transport mechanism to be the tunneling effect through

the oxide barrier.

B-100

PE-09

Spin-related effects in Heavy Metal/Ferromagnet/Antiferromagnet Layer Structure

C. Engel, S. Goolaup, W. S. Lew School of Physical and Mathematical Sciences,

Nanyang Technological, University, 21 Nanyang Link, Singapore 637371

e-mail: wensiang@ntu.edu.sg

Spin-Orbit Torque in heavy metal/ferromagnetic (HM/FM) layer structure has

recently attracted a lot of attention due to the possibility of magnetization switching [1,

2]. In three terminal spintronic devices the spin-orbit torque can deliver a fast and

reliable operation which separates the writing and reading path [3]. In a HM/FM layer

structure a current in the HM will produce the bulk spin Hall effect as well as the

Rashba effect occurring at the HM/FM interface. Similar effects are expected in an

antiferromagnetic (AFM) layer in contact with an FM layer. In this work, we report on

the electrical tuning of the coercivity of the FM layer in a HM/FM/AFM

heterostructure leading to a 70% decrease in coercivity as seen in Figure 1. This is

attributed to a current induced modification of the AFM states and spin-orbit torque

from the HM. As the bias current is increased, we observed that both the coercivity and

exchange bias field decreases.

Fig. 1: (a) shows resistance in relation to the external magnetic field for different AC

currents. (b) shows the coercivity and exchange bias against the AC current.

[1] I. M. Miron, et al., Perpendicular switching of a single ferromagnetic layer induced by

in-plane current injection, Nature 476, 189-193 (2011).

[2] L. Liu, et al., Spin-torque switching with the giant spin Hall effect of tantalum, Science

336, 555-558 (2012).

[3] M. Yamanouchi, et al., Three terminal magnetic tunnel junction utilizing the spin Hall

effect of iridium-doped copper, Appl. Phys. Lett. 102, 212408 (2013).

B-101

PE-10

Electric field effect on magnetoresistance of multiferroic heterostructures

Tomoyasu Taniyama(a), Junpei Okada(a), Mitsuru Itoh(a)

(a)Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan

Multiferroic heterostrcutures provide a promising material basis for designing novel spintronic devices that can be operated at very low energy consumption [1]. 90° or even 180° magnetization switching has been achieved by a pure electric field instead of using an electric current [2]. Since magnetoresistance (MR) is another critical property in a majority of spintronic devices, controlling MR by an electric field also could offer the breakthrough that opens up a pathway for exploiting new spintronic devices [3]. In this work, we investigate electric field effect on the MR of Co/Cu/Fe wire/ferroelectric (FE) BaTiO3 (BTO) heterostructures, where significant changes in the MR characteristics were demonstrated in the orthorhombic (O) phase of BTO.

2 m wide Co/Cu/Fe MR wire/BTO heterostructures were fabricated by using MBE followed by electron beam lithography and Ar ion milling. MR curves were collected while applying a transverse electric field using laterally located two electrodes as shown in Fig. 1. Typical MR curves are presented in Fig. 2. In the tetragonal (T) phase of BTO, the MR curves exhibit no changes even in electric fields while in the O-phase the MR curves are significantly varied in an electric field of ± 67 kV/cm. The drastic change in the MR should arise from strain transfer effect on the spin polarization and anisotropy of the Fe layer that is in contact with BTO. Since BTO has a multi-domain in the O- phase underneath the wire, the application of an electric field gives rise to efficient strain transfer to the Fe layer due to the FE polarization switching of BTO, leading to a marked variation in the spin dependent electronic structure and magnetic anisotropy. Detailed analysis also reveals that strain along the wire axis plays a key role in the variation of the MR we observe. [1] T. Taniyama, J. Phys.: Condens. Matter 27, 504001 (2015). [2] Y. Shirahata, T. Taniyama, et al., NPG Asia Mater. 7, e198 (2015). [3] S. Savitha Pillai, T. Taniyama, et al., Appl. Phys. Lett. 107, 072903 (2015).

Fig. 1 Photograph of a

GMR wire device on BTO. 4

3

2

1

MR

(%

)

100V 0V -100V

(a) T-phase

0

3

2

1

0-100 0 100

Magnetic Field (Oe)

(b) O-phase

Fig. 2 MR curves in the T- and O-phases of BTO in an electric field.

B-102

PF-01

Synthesis and high-frequency absorption property of

flower-like nickel-ferrite composites

Guangqiang Zhanga, Hangrong Dongb, Shaoxiong Zhoua, Min Zeng*b. aAdvanced Technology & Materials Co., Ltd., China Iron & Steel Research Institute

Group Co., Ltd., Beijing 100081, China bSchool of Materials Science and Engineering, Beihang University, Beijing 100191,

PR China

min_zeng@buaa.edu.cn

Three-dimensional flower-like nickel-ferrite composites have been successfully synthesized via decomposition of the nickel-iron alkoxide precursors by varying the ratio of iron and nickel ion in the solution. The overall morphology and size of the particles have no obvious change compared with the precursors. The high-frequency absorption properties of the composites are investigated in a frequency range of 2-18 GHz. The reflection loss and bandwidth vary with the nickel ratio and thicknesses of the compositions, showing valuable prospect in high-frequency wave attenuation. The wave absorbing mechanism is also discussed, which can be attributed to the dielectric loss, magnetic loss, and the synergetic effect.

B-103

PF-02

First to Second Order Phase Transformation in

La0.7-xSmxCa0.3MnO3 Compounds

Tran Dang Thanh(a), Dinh Chi Linh(b), Tien Van Manh(a), Le Viet Bau(c), and Seong Cho Yu(a)

(a)Department of Physics, Chungbuk National University, Cheongju 361-763, South

Korea (b)Institute of Materials Science, Vietnam Academy of Science and Technology,

Hanoi, Vietnam (c)Department of Engineering and Technology, Hong Duc University, Thanh Hoa,

Vietnam e-mail: thanhxraylab@yahoo.com

The magnetocaloric effect (MCE) was discovered a long time ago. It is the response of a magnetic material to the applied magnetic field change and appearing the maximum value when the material is near its magnetic ordering temperature. In recent years it has attracted the attention of researchers and the amount of publications in this topic increases quickly. It is known that first order magnetic phase transition La0.7Ca0.3MnO3 compound exhibits a giant MCE around the Curie temperature (TC). However, MCE in this compound only occurs in a narrow temperature range, which limits its applicability. In this work, we point out that the width and the nature of the magnetic phase transition, TC value, and as well as MCE in this material is easily modified through Sm-doped into La-site. With an increasing Sm concentration in La0.7-xSmxCa0.3MnO3 compounds, a systematic decrease in the magnetization, TC, and magnetic entropy change (ΔSm) are observed. The Banerjee criterion suggests that the sample with x = 0.1 considered undergoes a first order magnetic phase transition. Meanwhile, x = 0.2 sample undergoes a second order magnetic phase transition. A detailed analysis of the critical behavior based on the modified Arrott plots, the Kouvel-Fisher, and the scaling hypothesis methods has been done. Our results indicate a coexistence of long-range and short-range ferromagnetic interactions in La0.5Sm0.2Ca0.3MnO3 compound. Besides, a further method, a phenomenological universal curve for magnetic entropy change, has been applied as a supplementary criterion to discriminate between the first and second order phase transition in these samples. The essence of changes in the order of magnetic phase transition, magnetic and magnetocaloric properties is thoroughly discussed by means of the crystal structure.

B-104

PF-03

Magnetoresistance and Magnetocaloric Effects in La0.7Ca0.3Mn0.9Co0.1O3 Exhibiting the Crossover of First-

and Second-Order Phase Transitions

Tran Dang Thanh(a), Duong Anh Tuan(b), The Long Phan(c), and Seong Cho Yu(a)

(a)Department of Physic, Chungbuk National University, Cheongju 361-763, South

Korea (b)Department of Physics, University of Ulsan, Ulsan 680-749, Korea

(c)Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791, South Korea

e-mail: thanhxraylab@yahoo.com

Hole-doped perovskite manganites R1-xAxMnO3 have recently attracted considerable attention because of their unusual magnetotransport properties, such as magnetoresistance (MR) and Magnetocaloric (MC) properties. These properties of manganites arisen from two classes of competing effects: (i) charge and orbital orders cause insulating and generally antiferromagnetic-ordered ground state, and (ii) double-exchange (DE) interactions lead to metallic and ferromagnetic-ordered ground state. To get more insight into the relation between the MR and MC properties in the crossover of first- and second-order phase transitions materials, we have selected Co-doped into Mn-site in La0.7Ca0.3MnO3 compound to study.

In this work, a polycrystalline sample of La0.7Ca0.3Mn0.9Co0.1O3 was prepared by solid-state reaction method. Our results point out this compound exhibits the crossover of first- and second-order phase transitions. A coexistence of MR and MC effects in the La0.7Ca0.3Mn0.9Co0.1O3 compound, which takes place around the metal-insulator (MI) transition with TMI = 155 K and the ferromagnetic-paramagnetic (FM-PM) transition with TC = 188 K, respectively, has been observed. Considering temperature dependences of resistivity in the presence and absence of the magnetic field, ρ(T), data could be described by the phenomenological percolation model of phase segregation. This indicates electron-electron and electron-magnon scattering processes are dominant at temperatures below TMI. Further, based on modified Arrot plot and scaling analysis, the critical behavior around FM-PM phase transition of sample has been done. The obtained results suggest an existence of the ferromagnetic short-range order in La0.7Ca0.3Mn0.9Co0.1O3 compound. This nature of the observed phenomena is discussed thoroughly by mean of the coexistence and competition of magnetic interactions.

B-105

PF-04

The universal behavior in ternary equiatomic RETAl (RE = Er and Ho, T = Fe and Ag) compounds

Yikun Zhang a, b, *, Xi Li a, Zhongming Ren a, Gerhard Wilde b

a State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai

University, Shanghai 200072, China b Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Straße 10,

D-48149 Münster, Germany

Ternary equiatomic rare earth based RETAl intermetallic compounds have

attracted some attentions due to the exhibition of interesting physical and chemical

properties. Recently, the magnetic properties and magnetocaloric effect (MCE) in

RETAl systems have been reported systematically. In the present paper, we

investigated the universal curve for the rescaled SM (T) in RETAl (RE = Er and Ho, T

= Fe and Ag) compounds. The results indicated that the SM curves for the ErFeAl,

HoFeAl, ErAgAl and HoAgAl under various magnetic field changes can collapse onto

the one universal curve, respectively, confirming the second order phase transitions

occurred in RETAl compounds. The present results may provide some new data for

searching proper materials for active magnetic refrigeration.

References

[1] Yikun Zhang, G. Wilde, X. Li, Z. Ren, and L. Li, “Magnetism and magnetocaloric effect in the

ternary equiatomic REFeAl (RE = Er and Ho) compounds”, Intermetallics, 65 (2015) 61.

[2] Yikun Zhang, B. Yang, and G. Wilde, “Magnetic properties and magnetocaloric effect in ternary REAgAl (RE = Er and Ho) intermetallic compounds”, Journal of Alloys and Compounds, 619 (2015) 12

B-106

PF-05

Collective Magnetoresistance Effect of Ferromagnetic Microparticle Suspension

G. Jia(a,c), H.-G. Piao(a,b)*, D.-H. Kim(b), and S.-C. Yu(b) (a)CTGU Collaborative Innovation Center for Magneto-electronic Industry, College

of Science, China Three Gorges University, Yichang 443002, China (b)Department of Physics, Chungbuk National University, Cheongju 361-763, South

Korea (c)College of Electrical Engineering & New Energy, China Three Gorges University,

Yichang 443002, China *E-mail: hgpiao@ctgu.edu.cn

The study of magnetic micro-/nano-particle suspensions as a magnetorheology

material has been attracting much attention due to its possible applications in smart engineering as a kind of intelligent materials [1,2]. Recently, enhancement and/or controllability of the magnetoresistance (MR) effect have become important issues for applications of magnetic micro-particle suspensions [3]. The magnetic particle suspension is a dispersing liquid of micron-sized ferromagnetic metallic particles. As a flowable ferromagnetic metallic material without any field (it is not easy to flow under the magnetic field), it necessarily exists the MR effect under applied magnetic field. Therefore, understanding and control of the magnetic suspension MR effect is one of important topics for electrical applications of magnetic suspensions. In this work, we experimentally investigated the collective MR effect of magnetic micro-particle suspensions. The magnetic suspension is based on ferromagnetic carbonyl iron microparticles, which is dispersed in the silicone oil with various surfactants. The magnetic suspension MR effect was intensively examined with changing the strength and the direction of the external magnetic field. As shown in Fig. 1, we have observed that the electrical resistance of magnetic suspensions was affected by the strength and the direction of the external magnetic field. The magnetorheological effect is attributed to the collective dynamic behavior of microparticles in the magnetic suspension under the magnetic fields.

Fig. 1. Dependence of collective MR effect on the magnetic field.

[1] J. D. Carlson, D. M. Catanzarite and K. A. St. Clair, Int. J. Mod. Phys. B 10, 2857 (1996). [2] W. I. Kordonski and S. D. Jacobs, Int. J. Mod. Phys. B 10, 2837 (1996). [3] D. Yang, L. Du, Z. Xu, et al., Appl. Phys. Lett. 104, 061903 (2014).

B-107

PF-06

Photo-enhanced ferromagnetism in high K+-containing K-Ni-Cr Prussian blue analogues coated on Rb-Co-Fe

nanocubes Chi-Hung Lee,a Min-Yung Wang,a Erdembayalag Batisakhan,a Chun-Ming Wu,b

Chin-Wei Wang,b and Wen-Hsien Lia,* aDepartment of Physics, National Central University, Jhongli 32001, Taiwan

bNeutron Group, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan e-mail: k010211@yahoo.com.tw

Many fascinating magnetic behaviors have been identified in Prussian blue analogues (PBAs) with a general chemical formula of AxM[M(CN)6]y·nH2O (denoted as A-M-M), where M and M can be divalent or trivalent transition metal ions and A is a monovalent alkali ion that is accommodated in the voids enclosed by the MN6 and MC6 octahedra. Their magnetic characteristics depend not only on the intrinsic nature of the complexes, but can also be greatly altered by extrinsic stimulations, such as the applied pressure or light irradiation.[1-3] In particular, one very promising characteristics is the photo-induced magnetism found in A-Co-Fe (with A = K, Na, Rb, Cs), which has been demonstrated to be sensitive to the type and the amount of A+ ion that has been incorporated into the compound.[1-3] This behavior is believed to originate from the electron transfer that occurs between the MN6 and MC6 octahedra, known as the charge transfer induced spin transition (CTIST).[4]

In addition, the photo-magnetic responses in nano-sized core/shell heterostructures have recently been found to be sensitive to the shell thickness.[5-7] No photo-induced magnetism has been identified in isolated K-Ni-Cr, but noticeable reductions (~8%) of the magnetization by light irradiation appear when this material is coated on a Rb-Co-Fe nano-cube.[5]

Here, we demonstrate that K-Ni-Cr can become photoactive in high K+-containing compound. Significant increases of the Ni as well as Cr magnetic moments upon UV light irradiation were detected in a 55 nm thick high K+-containing K-Ni-Cr shell coated on a 240 nm Rb-Co-Fe cube. Surprisingly, the photo-enhancement of the magnetic moments for the K0.98-Ni-Cr0.70 phase is as large as that for the Rb0.76-Co-Fe0.74 phase (Fig.1). It is the considerably larger amount of K+ ions incorporated into the compound, leading to the greater electron distribution near the bridging C-N ions (Fig.2) that strengthens the electronic connection in the Ni-N-C-Cr-C-N-Ni chains giving rise to a better photo-magnetic sensitivity in the present K-Ni-Cr PBA network.

[1]O. Sato et al., Science, 1996, 272, 704-705.

[2]O. Sato et al., Inorg. Chem., 1999, 38, 4405-4412.

[3]S. Ohkoshi et al., Chem. Mater., 2005, 17, 81-84.

[4]C. Chong et al., Phys. Rev. B, 2011, 84, 144102.

[5]M. F. Dumont et al., Inorg. Chem., 2011, 50, 4295-4300.

[6]N. R. Olivia et al., J. Am. Chem. Soc., 2014, 136, 15660-15669.

[7]D. M. Pajerowski et al., Phys. Rev. B, 2015, 91, 094104.

[8]C.-H. Lee et al., J. Phys. Chem. C, 2015, 119, 29138-29147.

30 40 50 60 70

-2

0

2

4

(220

)

(20

0)

Rb-Co-Fe@K-Ni-Cr

Net

inte

nsi

ty (

104 c

oun

ts)

Scattering angle 2 (deg.)

Neutron

ILight

- IDark

3 K

(111

)

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Cr

Ni e/Å3

a (r.l.u.)

b (r

.l.u.

)

-3.000

-2.000

-1.000

0

1.0001.500(c)(0 0 0.08)

Ni

Cr

Figure 1 Difference intensities between the neutron diffraction pattern taken with and without light irradiation at 3 K.

Figure 2 Differences of the electronic charge density

between the present Rb0.76-Co-Fe0.74@K0.98-Ni-Cr0.70 and

the Rb0.48-Co- Fe0.74@K0.36-Ni-Cr0.74 (non-photomagnetic)

reported in Ref. 8 (0 0 0.08) crystallographic planes.

B-108

PF-07

Additive Manufacturing of Cobalt-based Organic Ferromagnetic Materials

Junfeng Huang(a), Winco K.C. Yung(a), Zhengong Meng(b), Desmond T.C. Ang(a), Hang Shan Choy(a), Guijun Li(a)

(a)Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong

(b)Department of Chemistry, Hong Kong Baptist University, Hong Kong e-mail: carl.huang@polyu.edu.hk

Inkjet printing of magnetic materials with 3D structures has aroused a remarkable interest in recent years [1,2]. However, patterning of ferromagnetic materials using inkjet printing is still challenging. Here, 3D magnetic components are structured using inkjet printing with ferromagnetic molecules. Cobalt based ferromagnetic organic molecules were synthesized using chemical methods as shown in Fig. 1. The synthesized molecules can be dissolved in organic solvents such as acetonitrile and dimethylformamide. These solvents are compatible with the commercial inkjet printing. The ferromagnetic nature of the synthesized organic molecules was verified by vibrating sample magnetometer (VSM) with the magnetization up to 0.25 emu/g as Fig. 2 shows. Taking advantage of inkjet printing, the synthesized ferromagnetic molecules can be patterned onto artificial 3D structures. Unlike dispersed nanoparticle, the completely soluble organic molecules would not face clogging issues caused by agglomeration [3]. Their microstructures and magnetic properties after inkjet printing were experimentally studied. The potential applications of these 3D printed ferromagnetic materials were also explored.

[1] Y. Wu, K. V. Rao, W. Voit, T. Tamaki, O. D. Jayakumar, L.

Belova, Y. S. Liu, P. A. Glans, C. L. Chang and J. H. Guo, IEEE

Transactions on Magnetics, 46, 2152 (2010)

[2] G. Li, R. C. Roberts and N. C. Tien IEEE SENSORS,

2014 IEEE; p 1687, (2015)

[3] K. Yung, S. Wu and H. Liem, Journal of Materials

Science, 44, 154 (2009)

Fig. 1 Cobalt base

molecular structure

Fig. 2 Hysteresis loop

for Cobalt base organic

B-109

PF-08

Current induced skyrmion dynamics via spin orbit coupling types

Seung-Jae Lee(a), Kyung-Jin Lee(a), (b) (a)KU-KIST Graduate School of Converging Science and Technology, Korea

University, Seoul, Korea (b)Department of Materials Science and Engineering, Korea University, Seoul

Korea e-mail: kj_lee@korea.ac.jp

In magnetic system with large spin-orbit coupling (SOC) and inversion asymmetry, the Dzyaloshinskii-Moriya interaction (DMI) becomes non-negligible [1, 2]. Recently magnetic skyrmions stabilized by DMI are expected to have potential as information unit for storage and logic devices [3]. There are two types of SOCs in skyrmion studies. One is for Rashba SOC induced by structural inversion asymmetry. The other is Weyl SOC induced by bulk inversion asymmetry, typically observed in B20 structures. However, studies on magnetic skyrmion stabilized by Dresselhaus SOC have lacked. The Dresselhaus SOC is induced by bulk inversion asymmetry [4], and its magnitude can be similar to that of Rashba SOC [5]. In this work, based on micromagnetic simulation, we investigate current-induced skyrmion dynamics in ferromagnet nanowire with three types of SOCs. We consider DMI and spin orbit spin transfer torque (SOT) having the symmetry with the corresponding SOC.

Figure 1 shows that the skyrmion velocity is linearly dependenct on the current density, consistent with the prediction based on collective coordinate approach. For all types of SOCs, the skyrmion velocity are given by Dv SOT

x /F (current flow in x-axis) and Gv SOTx /F (current flow in

y-axis) [6], where α is the damping constant, D is the factor of disspation matrix, G is the magnitude of gyrovector and eh eSHE

SOT 4/JF is the force originating from spin orbit spin transfer torques. These results are explained by the same symmetry in both SOT and DMI for a given SOC.

Fig. 1 Skyrmion velocity as a function of current density J for different current flow direction. (a) DM induced by Dresselhaus SOC, (b) Rashba SOC, and (c) Weyl SOC [1] I. E. Dzyaloshinskii, Sov. Phys. JETP 5, 1259 (1957) [2] T. Moriya, Phys. Rev. 120, 91 (1960) [3] A. Fert, V. Cros & J. Sampaio, Nature Nanotechnology 8, 152–156 (2013) [4] G. Dresselhaus, Phys. Rev. 100, 580 (1955) [5] N. A. Sinitsyn, Phys. Rev. B 70, 081312 (2004) [6] M. E. Knoester, Phys. Rev. B 89, 064425 (2014)

B-110

PF-09

Detrimental Effect of Interfacial Dzyaloshinskii-Moriya

Interaction on Perpendicular Spin-Transfer-Torque Magnetic Random Access Memory

Ik Sun Hong(a), Peong Hwa Jang(b), K.-J. Lee(a),(b) (a) KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul

136-713, Korea (b) Department of Materials Science and Engineering, Korea University, Seoul 136-713, Korea

e-mail: kj_lee@korea.ac.kr Recently, perpendicular magnetic anisotropy based spin-transfer torque magnetic random access

memory (STT-MRAM) is drawing a great attention to researchers studying MRAM due to its advantages of having the density of DRAM, fast response time of SRAM and the non-volatility of flash memory [1]. Moreover, recent studies has shown that the spin orbit coupling ,which results in the interfacial perpendicular magnetic anisotropy, and the inversion symmetry breaking at the interface between free layer and heavy metal of magnetic tunnel junction (MTJ) results in antisymmetric exchange interaction named as Dzyaloshinskii-Moriya interaction (DMI).[2]

We numerically studied the effect of DMI and size of the cell on switching current density (Jsw) at room temperature and thermal stability )/( TkE B0 at 0K which are the important factors for commercialization of STT-MRAM. [3] We used 1×10-6 erg/cm for exchange stiffness constant, 1×107

erg/cm3 for anisotropy constant, 1000 emu/cc for saturation magnetization and 0~1 erg/cm2for DMI constant for cells with diameter of 10,15,20,30 nm. First, we studied the effects of DMI and cell diameter on the thermal stability that is a good parameter for determining the retention time of the data. According to our study with String method [4], the larger DMI constant lead to the smaller thermal stability as shown on Figure 1(a). Next, we calculated the switching current density at room temperature as a function of DMI constant. We found that the current density increased as DMI constant got larger due to its tendency to keep its skyrmion number maintained. [5] In conclusion, we showed that DMI deteriorates both the switching current and the thermal stability of the device. Hopefully, the DMI effect vanished as the device diameter, as required in the commercialization of STT-MRAM, got smaller.

Figure 1: (a) Normalized thermal stability as a function of DMI constant. (b) Switching current density as a function of

DMI constant. Both thermal stability and switching current density is less effected by DMI constant as the diameter of the

cell is decreased.

[1] A V Khvalkovskiy et al., J. Phys. D: Appl. Phys. 46, 139601 (2013)

[2] T. Moriya, Physical Review 120, 91 (1960).

[3] J. Z. Sun et al., Phys. Rev. B 88, 104426 (2013).

[4] Weinan E, Weiqing Ren, Eric Vanden-Eijnden, , J. Chem. Phys., 126, 164103.

[5] R. S. Ward, Lett.Math.Phys. 35 (1995) 385-393

B-111

PF-10

Excitation Properties of Surface Plasmon of Non-Solid-Solution Ag-(Co, Fe) Thin Films

Yusuke Tada(a), Toru Tachikawa(a) , Yoshito Ashizawa(b), and Katsuji Nakagawa(b)

(a) Graduate School of Science and Technology, Nihon University, Chiba, Japan. (b) College of Science and Technology, Nihon University, Chiba, Japan.

e-mail: tada_yuusuke@inl.ecs.cst.nihon-u.ac.jp

Surface plasmon, which is very sensitive to change in dielectric constant of medium, is a remarkable phenomenon to be applied to a sensor. We reported magnetic activity of surface plasmon using films with noble metals and magnetic metals for realizing a magnetic sensor. We focus on a single layer structure using non-solid-solution Ag-(Co, Fe) metals. The excitation of surface plasmon strongly depends on composition and film thickness, so it is important for improvement the properties of surface plasmon to regulate those parameters. In this study, the properties of surface plasmon of Ag-(Co, Fe) thin films were investigated.

Specimens were deposited on glass substrates by RF magnetron sputtering method. Surface plasmon was excited and detected by attenuated total reflection method in Kretschmann-Raether configuration. The wavelength of incident light was 700 nm. External magnetic field of 400 mT was applied to normal direction to the film plane by a permanent magnet.

Reflectivity of Ag-(Co, Fe) films were measured and calculated as a function of incident angle. Figure 1 shows a difference between maximum and minimum reflectivity, Rmax-Rmin and a maximum absolute gradient of the reflectivity curve, |dR/d|max of Ag75Co25 films as a function of film thickness. We used dielectric constants of Ag and Co with the ratio Ag:Co = 3:1 for calculation. The Ag75Co25 film with 35 nm-thick shows the largest Rmax-Rmin. The |dR/d|max is increased with thinning the thickness of the Ag75Co25 films down to 35 nm. Calculated values agreed well with measured values. Acknowledgment

This work is partially supported by a Grant of MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2013-2017. [1] T. Tachikawa, Y. Ashizawa, and K. Nakagawa: J. Magn. Soc. Jpn.,38, 135-138 (2014).

Fig. 1 A difference between maximum and minimum Rmax-Rmin and a maximum absolute gradient of the reflectivity curve, |dR/d|max of Ag75Co25 films as a function of film thickness[1].

B-112

PF-11

Substitution-modified optical and magnetic properties of La doped BaTi0.9Fe0.1O3

D. H. Kim(a), Pardi S. Tola(a), and B. W. Lee(a,b)

(a) Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin, Gyeonggi 449-791, South Korea

(b) e-mail: bwlee@hufs.ac.kr

In this work, we studied the crystal structure, optical, and magnetic properties of La3+ doped BaTi0.9Fe0.1O3 (Ba1-xLaxTi0.9Fe0.1O3) polycrystalline ceramics. Ba1-xLaxTi0.9Fe0.1O3 ceramics were prepared by a conventional solid state reaction method. The XRD spectra revealed that a phase transformation from hexagonal to tetragonal phase took place gradually in this series as the La3+ content increased. The Raman scattering and photoluminescence spectra further confirmed the change in the crystal structure observed from the XRD results. Obvious ferromagnetic ordering was observed in samples with x less than 0.1 by the field-dependent magnetization measurement at room temperature. The saturated magnetization and magnetic remanence were also found to be controlled by La3+ doping. The magnetic phase transition temperature calculated from the temperature-dependent magnetization measurement from 300 K to 800 K showed obvious dependency of La3+ concentration as well. Our observation confirmed that the variations of the physical properties induced by La3+ doping is intrinsic.

B-113

CA-01

Magnetic Anisotropy - How much is enough for a

permanent magnet?

J. M. D. Coey

School of Physics and CRANN, Trinity College, Dublin 2, Ireland

A permanent magnet must have a microstructure that impedes nucleation and

growth of reversed domains, allowing it to retain its metastable, highly-magnetized

state. Since the purpose of a magnet is to create flux is surrounding space, the

paramount figure of merit is energy product (BH)max,, with an upper bound of ¼µ0Ms2

where Ms is the saturation magnetization. Hard materials choices can be analyzed in

terms of an intrinsic hardness parameter = (Ku/µoMs2)1/2, where Ku is the uniaxial

anisotropy energy constant. As a rule of thumb, should be at least 1 if there is to be a

prospect of fabricating a material into a permanent magnet of any desired shape; the

larger , the easier the processing becomes.

Hexagonal ferrites, CoPt, Nd2Fe14B, and other rare earth magnets all have

significantly greater than 1. The magnetization therefore determines how much

anisotropy is required to provide adequate hardness. Although it is possible to make

permanent magnets from materials with low values of , they have the drawback that

they will only retain their magnetized state if they have certain shapes. Shape

anisotropy, exploited in special steels and Alnico, can never provide > 1/√2. Despite

apparently-impressive anisotropies of 1- 2 MJ/m3 many of the transition-metal alloys

presently investigated as potential rare-earth-free permanent magnets are of this

semi-hard type. Some potential new magnets and alternative strategies to develop

magnetic hardness are discussed.

B-114

CA-02

Optimization of the magnetic properties of hot deformation NdFeB magnets

Y. I. Lee(a), S. T. Chang(a), G. Y. Huang(a), C. W. Shih(a), W. C. Chang(a), H. W. Chang(b) and Y. J. Chen(c)

(a)Department of Physics, National Chung Cheng University, Chia-Yi, 621 Taiwan.

(b)Department of Physics, Tunghai University, Taichung, 407 Taiwan. (c)Metal Industries Research & Development Center, Kaohsiung, 81160, Taiwan.

e-mail: phywcc@ccu.edu.tw

High performance R2Fe14B-type magnets have been developed since 1983. They became the most powerful magnets for the application in high precision/high power motors, consumer electronic devices, MRI, and wind turbines, etc., since then. Many kinds of methods have been reported to make R2Fe14B-type magnets with high magnetic properties to meet the wide applications. The most promising method is using the powder metallurgy which could produce the highest energy product magnets. The second one is the isotropic bonded magnets made with the rapidly solidified R2Fe14B ribbons in combination with epoxy to form the magnets with various shapes. Other methods, such as hot deformation, i.e. hot press plus die upset, could also develop high performance anisotropic R2Fe14B-type magnets, which provide a variety of application in many fields. Nevertheless, the magnetic properties of the latter magnets made with different hot deformation condition, including the grain size homogeneity and density of the hot-pressed MQII preform, the reduction ratio and thermal processes, will be affected owing to the change of (00L) texture and grain morphology after processing. In this presentation, the effect of alloy composition and the factors that may affect the (00L) texture and microstructure, and the correlation of grain size and grain morphology with magnetic properties of hot deformation NdFeB magnets will be introduced.

B-115

CA-03

High-Aspect-Ratio magnetic nanoparticles for Future

Permanent Magnets

J.P. Liu Department of Physics, University of Texas at Arlington

It is of a grand challenge to develop strong magnetic anisotropy in nanostructured bulk permanent magnets. In a decade long effort, we have worked on bottom-up approaches to produce anisotropic nanostructured magnets made from hard and soft magnetic nanoparticles. The approaches start from synthesis of ferromagnetic nanoparticles, especially the high-aspect-ration nanoparticles by applying newly developed “salt-matrix annealing”, “surfactant-assisted ball milling” and modified solvothermal synthesis techniques. We have successfully synthesized monodisperse nanorods, nanowires and submicron chips of ferromagnetic FePt, FeCo, CoNi, CoCx and Co, as well as NdFeB and SmCo based materials. These first-ever-available nanoparticles display various hard and semi-hard magnetic properties at room temperature which are found to be strongly size and morphology dependent, attributed to the finite size effect and shape anisotropy effect. The submicron SmCo and NdFeB based chips by the ball milling process can be aligned in a magnetic field to form anisotropic assemblies with high coercivity up to 20 kOe. The aligned Co nanowires have their coercivity values exceeding 10 kOe and energy product exceeding 40 MGOe. The ferromagnetic nanoparticles are used as building blocks for advanced bulk and thin film permanent magnets, and can be also applied in biomedicine and ferrofluid technologies.

B-116

CB-01

Spin Current Generators

Eiji Saitoh(a-d)

(a)ERATO-SQR, JST, Japan (b)WPI-AIMR, Tohoku University, Japan

(c)Institute for Materials Research, Tohoku University, Japan (d)ASRC, JAEA, Japan

I will give an introduction to the concept and various fascinating phenomena of

spin-current science. Generation and utilization of spin current, a flow of spin angular momentum of electrons in condensed matter, are the key challenge of today’s nano magnetism and spintronics. The discovery of the inverse spin Hall effect has allowed researchers to detect and utilize spin current directly, and, since then, many spin-current driven effects have been discovered, including spin Seebeck effects, light-spin conversion, sound-spin conversion, and motion-spin conversion. Spin Seebeck effects refer to spin-current generation from a temperature gradient, where spin’s non reciprocity allows it to rectify thermal fluctuation into unidirectional spin current; spins, working as a natural rectifier in magnets, may thus provide a versatile mechanism of energy conversion in condensed matter. Spin micro mechanics, one of more recent topics, will also be covered.

B-117

CB-02

Theory of magnetic insulator | metal bilayers

Gerrit E.W. Bauer(a,b)

(a)IMR, Tohoku University, Sendai, Japan (b)Kavli Institute of NanoScience, TU Delft, The Netherlands

e-mail: g.e.w.bauer@imr.tohoku.ac.jp; g.e.w.bauer@tudelft.nl

Spintronics based on magnetic and non-magnetic elemental metals and their alloys has been very successful in the last decades. Discoveries such as the giant magnetoresistance, tunnel magnetoresistance, spin-transfer torque, (inverse) spin Hall effect, spin-orbit torques etc. not only led to fundamental new physical insights, but also to new functionalities that are employed in new nanoscale devices such as switches, memories, and sensors.

Magnetic insulators form another class of versatile materials with great technological importance. They have been central to the research in magnetism up to the 80’s of the last century, but were later largely forgotten by the physics community. The most important magnetic insulators are arguably the man-made yttrium iron garnets, ferrimagnets with Curie transitions far above room temperature and record magnetic quality [1-2]. K. Uchida, E. Saitoh c.s. demonstrated that magnetic insulators can be actuated thermally and electrically by metallic contacts. This attracted much interest since it allows for their integration into conventional electronic and thermoelectric devices. The discovery of entirely new phenomena, such as the spin Seebeck effect, raises the hope for a new and green spintronics.

This talk reviews recent progress in the theoretical spin(calori)tronics of YIG and its heterostructures with normal metals, addressing recent results on spin injection and transport in magnetic insulators, spin magnetoresistance, and coupling of the magnetization with phonon and photon fields.

This work was supported by the FOM Foundation, Reimei program of the Japan Atomic Energy Agency, EU-FET “InSpin”, the ICC-IMR, DFG Priority Program 1538 “Spin-Caloric Transport”, and JSPS Grants-in-Aid for Scientific Research (Grant Nos. 25247056, 25220910, 26103006).

[1] V. Cherepanov, I. Kolokolov, V. L'vov, The Saga of YIG: Spectra,

Thermodynamics, Interaction and Relaxation of Magnons in a Complex Magnet, Phys. Rep. 229, 81 (1993).

[2] Recent Advances in Magnetic Insulators -- From Spintronics to Microwave Applications, M. Wu and A. Hoffmann (eds.), Solid State Physics 64, 1 (2013).

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Fully Functional 64Mb STT-MRAM Utilizing Advanced pMTJ on 300mm Wafers

Yiming Huai*, E. Abedifard, J. Zhang, Y. Zhou, X. Wang, Z. Wang, X. Hao, D. Jung, K. Satoh, B. Yen, H. Gan,

K. Moon, U. Chandrasekhar

Avalanche Technology, 46600 Landing Pkwy, Fremont, CA 94538

We report industry’s first 64Mb perpendicular MTJ (pMTJ) spin transfer torque magnetic

random access memory (STT-MRAM) chip fabricated in a top tier 300mm foundry using the standard 55nm CMOS foundry process [1][2][3]. Our fully functional 64Mb chips deliver the best combined attributes among existing memory technologies, with >10 year retention at 150oC, fast read/write speed <20ns and superb endurance beyond 1015 cycles at the pMTJ operating voltage.

Avalanche’s 64Mb STT-MRAM chips are designed with advanced and universal BEOL integration scheme [4], which is scalable down to 1X nm and suitable for both stand-alone and embedded applications. Only one photo masking step is used to etch pMTJ stack and bottom electrode (BE). Unlike the conventional two-mask MTJ etch process, this scheme significantly improves scalability and reduces process cost. Our pMTJ stack incorporating novel material engineering has demonstrated to withstand thermal stress throughout BEOL. This advanced scheme paves the way for pMTJ integration between any two metal layers, making it a universal and portable approach for both stand-alone and embedded applications. We also developed chemical-damage-free IBE process that enables STT-MRAM technology to scale down to 1X nm technology node.

Our advanced pMTJ exhibits TMR>200% at RA of ~10 Ωµm2 in thin pMTJ (<15nm) stacks with CoPt and/or CoNi pinning layers. Our device TMR is thermally stable up to 400°C for more than 120 min anneal, making it compatible with foundry BEOL process. Our pMTJ device has balanced off-set field with tail bit coercivity above 1500 Oe. Reliability measurement shows that our pMTJ can achieve endurance beyond 1015 cycles at the pMTJ operating voltage [5]. In the presentation, we will show write shmoo of the 64Mb chip operating at different speeds. Low ppm level bit error rate and high raw bit yield (>99.999% No ECC) are achieved. Chip raw error counts as a function of baking time at different temperatures are also measured. Data shows our chip achieves >10 year retention at 150°C. The error statistics of full-chip cycling remains stable up to 107 program cycles (test time limited). Fully functional chip performance has been achieved with ECC. References [1] Y. Huai et. al., International Workshop: Spintronics VLSI, Sendai, Japan (2015). [2] Y. Huai, session 204-A, Flash Memory Summit (2015). [3] Y. Huai et.al. AB-07, invited, INTMAG Conference (2015). [4] J. Zhang et.al. FS-14, MMM (2014). [5] X. Wang et.al. APEX, 7, 083002, (2014).

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CB-04

Magnetic bubblecade memory based on chiral domain walls

Kyoung-Woong Moon(a), Duck-Ho Kim(b), Sang-Cheol Yoo(b),(c), Soong-Geun Je(b), Byong Sun Chun(a), Wondong Kim(a),

Byoung-Chul Min(c), Chanyong Hwang(a) & Sug-Bong Choe(b)

(a)Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea.

(b)CSO and Department of Physics, Seoul National University, Seoul 151-742, Republic of Korea.

(c)Spin Convergence Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.

Unidirectional motion of magnetic domain walls is the key concept underlying

next-generation domain-wall-mediated memory and logic devices. Such motion has been achieved either by injecting large electric currents into nanowires or by employing domain-wall tension induced by sophisticated structural modulation. Herein, we demonstrate a new scheme without any current injection or structural modulation. This scheme utilizes the recently discovered chiral domain walls, which exhibit asymmetry in their speed with respect to magnetic fields. Because of this asymmetry, an alternating magnetic field results in the coherent motion of the domain walls in one direction. Such coherent unidirectional motion is achieved even for an array of magnetic bubble domains, enabling the design of a new device prototype—magnetic bubblecade memory—with two-dimensional data-storage capability. Reference : [1] Soong-Geun Je et al., Phys. Rev. B 88, 214401 (2013). [2] Kyoung-Woong Moon et al., Scientific Report 5, 9166 (2015).

B-120

CB-05

Grand design of novel spintronic and electronic materials for

next generation spintronics and electronics

Xiaolin Wang*

Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Australia

*Email: xiaolin@uow.edu.au

Discovery of new classes of materials with new functionalities or significantly improved performance

has always been the driving force for the advance of modern science and technology, and the

improvement of our daily lives. Searching for new class of materials with exotic properties has always

been challenging because of the complexity of both the theoretical and the experimental approaches

developed so far. This talk will present a number of new strategies we have developed for the design

of new materials and properties. It is expected to show how complicated science and materials design

could be made simple and enjoyable. We will discuss how new electronic materials can be designed

by shaping electronic band structures. A few examples such as Dirac massless Fermions in graphene

and surface or edge states of topological insulators, Weyl metals etc will be discussed. Emphasize on

a new class of materials, spin gapless semiconductors with exotic band structures, spin, charge and

momentum relations as well as their realization in practical compounds will be presented. It will be

shown that the spin gapless semiconductors are new and ideal platform for spintronics, massless

spintronics, quantum anomalous Hall effect, and new electronic and spin states. Furthermore, the

ultimate questions in material and property’s design are raised: 1) How many new (electronic)

materials or new (electronic) properties are still there? 2) What are they? 3) Where are they or how

to create them? To answer these questions, a new concept, the codes of matter/materials based on the

three ubiquitous and paramount attributes of all existing matter/materials, charge, spin, freedom of

motion will be introduced. We will discuss the principles of the codes and their applications in

material and property design. Many new types of electronic materials with exotic band

structures/properties and their possible experimental realizations will be discussed.

This work was financially supported by Australian Research Council through ARC discovery projects and Future

Fellowship project.

References: 1). X. L. Wang, “The codes of matter and their applications” Science Bulletin, 60, 1661-1673 (2015). 2). X.L. Wang, “A proposal for a new class of materials: Spin gapless semiconductors”, Phys Rev Lett. 2008 Apr 18;100(15):1564042. 3). X.L. Wang, S. X. Dou and C. Zhang, [Review Article], “Zero-gap materials for future spintronics, electronics and optics” NPG Asia Materials 2, 31-38 (2010)

B-121

CB-06

Study of Structural and Magnetism of Praseodymium- doped CeO2 Nanoparticles

William Lee(a), Shih-Yun Chen(a), Cheng-Wei Ku(a), Jun-Han Chen(b), Hsiang-Lin Liu(b)

(a)Department of Materials Science and Engineering, National Taiwan University

of Science and Technology, Taipei, Taiwan (b)Department of Physics, National Taiwan Normal University, Taipei, Taiwan

e-mail: d10104017@mail.ntust.edu.tw

In this study, we report on the successful synthesis of Pr-doped CeO2 (CeO2:Pr) nanoparticles (NPs) using a co-precipitation method while setting the Pr-content in the range from 0 to 15 atom %. The as-prepared samples were characterized in regard to their structural, morphological and magnetism. At first, crystal structure was characterized by X-ray Diffraction. X-ray Absorption Spectroscopy (XAS) and Raman spectroscopy were utilized to investigate the electronic structure of these NPs. Then ferromagnetism was studied by Vibrating Sample Magnetometer (VSM) at room temperature.

It is demonstrated that as raising the content of Pr, the degree of oxygen deficiency was enhanced monotonically, suggesting that oxygen and/or oxygen-related vacancies was induced. XAS analysis indicated the preference of the Pr-ions for the Pr3+ oxidation state, although small amounts of the Pr4+-ions could not be completely ruled out, in particular for the lightly doped ones. The charge state of Ce ions also changed as increasing Pr content, it towards 4+ gradually. Also, it is observed that both the distribution of Pr ions and oxygen vacancies was inhomogeneous. Together all spectroscopic results, the structure and evolution of above oxygen related defect was then unraveled. Furthermore, all the Pr-doped CeO2 NPs were found to be ferromagnetic at room temperature. The concentration dependence of dopant as well as defect on magnetism was shown and compared to other doped CeO2 NPs. At last, the relationship between defect structure and magnetic behavior of Pr-doped CeO2 NPs was derived.

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CB-07

Study on giant spin-orbit torque in perpendicular magnetization Pd/CoFeB structure

P.C. Chen, Y. Du, C.H. Lai

National Tsing Hua University, Hsin-chu, Taiwan

e-mail :gracefeather@yahoo.com.tw

Switching of perpendicular magnetized free layer in magnetic tunneling junction (MTJ) has been a popular topic recent years. By utilizing both spin Hall effect (SHE) and Rashba effect, one can achieve a successfully switching with the injection of a current into the under-layer made of certain heavy metal. With the definition of spin Hall angle (SHA), which indicates the effectiveness of generating spin current, people believe that the heavy metals with large SHA in value are reliable to be a candidate for under-layer material. According to studies up to date, such heavy metals as Ta, W, Pt, Bi etc. meet the requirement and are either generating strong spin current or create a Rashba field to accomplish switching.

At the other hand, some metals such as Ru, Pd and Mo are predicted to have weak SHA, which cannot meet the use for an efficient operation of a MTJ. Our study shows that when placed under certain conditions, the value of SHA of Pd can grow up to 30%, which is almost reaching twice larger than that of Ta. At the same time, we also manufactured a patterned device and indeed saw a successfully switching with a current density of 1.5x107 A/cm2 in a pulse width of 10μs. We expect that the phenomena of giant spin Hall effect in Pd can also be existing in other cases.

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CC-01

Opportunities for Neutron Scattering in Spintronic Thin Film Materials Science

Frank Klose(a), (b), G. L. Causer(a), (c), D. L. Cortie(a)

(a)Australian Nuclear Science and Technology Organisation, Lucas Heights,

Australia (b) The City University of Hong Kong, China SAR

(c)University of Wollongong, Wollongong, Australia

Basic science has revealed novel magnetic materials or magnetic effects which, in

principle, show promise to be deployed in future magnetic electronics or storage devices. A particularly promising area is spintronic materials. However, many of the most promising materials only work under extreme conditions such as very low temperatures or large magnetic fields. The big challenge is to understand the physics of these often artificially structured and engineered materials at the atomic or nanometer level and to make them work at room-temperature.

In order to characterise new magnetic properties which are often caused by interface or finite size effects, neutron scattering techniques such as polarised neutron reflectometry (PNR), SANS and diffraction are very powerful tools. These techniques have the capability for characterising the magnetic structures of artificially layered films from the micron down to the sub-nanometre scale.

Despite still being a relatively "slow" magnetic measurement technique, neutron scattering experiments are often the key to explaining the underlying physics as they provide information that is only accessible using the unique combination of properties provided by the neutron particle.

This talk will review the current state-of-the-art and present striking examples

which illustrate the usefulness of neutron quantum beams in magnetic thin film and spintronics research. The first example is a spin-polarised neutron reflectometry study on Co implanted TiO2 which demonstrates that giant magnetic moments up to 2.9μB per cobalt, not seen before in rutile or anatase, emerge from lightly Co doped regions of the amorphous TiO2 matrix [1]. The second example is a PNR study on ion beam irradiated FePt3 [2]. Here, the ion irradiation transforms AFM chemically ordered FePt3 into a chemically disordered state from which a distinct exchange bias effect emerges. [1] D. L. Cortie et al., submitted [2] G. L. Causer et al.

B-124

CC-02

Magnetic and structural phenomena underlying large magnetic-field-induced strains in a ferromagnetic

Heusler Ni-Mn-Ga alloy

A. Pramanick

Department of Physics and Materials Science, City University of Hong Kong, TatChee Avenue, Kowloon, Hong Kong

Materials that exhibit fast and large reversible shape changes upon application of external magnetic fields are desirable for magnetomechanical/ electromechanical energy transduction, mechatronics and biomedical devices. Recently, ferromagnetic martensitic alloys such as Ni-Mn-Ga have been particularly promising in this regard. However, further advances in materials and devise technologies will require a comprehensive understanding of the microscopic origins of their magnetostructural phenomena. In this regard, results from recent diffraction experiments, first principle calculations and phenomenological modeling are presented that provide crucial insights in these areas. Fundamentally, large magnetic-field-induced strains in ferromagnetic martensites arise from a large magnetocrystalline anisotropy, which was obtained here from both the inelastic neutron scattering experiments and the fully relativistic electronic structure calculations. The anisotropic classical Heisenberg model Hamiltonian was adopted to describe the magnetic properties of the system. The applicability of the obtained Hamiltonian was verified by comparing the theoretically obtained spin waves with that of experimental results. Microscopically, a strong spin-orbital coupling for Ni2Mn1.14Ga0.86 results in a reorientation of the martensitic twins when a magnetic field is applied along the magnetic hard axis. In order to measure directly the extents of both magnetic moments rotation and crystallographic twin-reorientation in an FSMA single crystal during the application of magnetic fields, in situ polarized neutron diffraction experiments were undertaken. In addition, the temporal evolution of twin reorientation under magnetic fields was characterized by time-resolved X-ray diffraction experiments. Based on these experimental results, the energy for magnetoelastic twin boundaries propagation for the studied alloy is

estimated to be ∼150 kJ/m3. Furthermore, it is shown that motion of magnetoelastic twin boundaries in this alloy can be described as a thermally activated creep over a distribution of energy barriers, which is mediated by competition between the longer range elastic fields of twin boundaries and the short-range elastic fields of dislocations.

B-125

CC-03

Complex magnetic phases and magnetic incommensurability in type-II multiferroic Co3TeO6

Wen-Hsien Li(a), Chi-Hung Lee(a), Chin-Wei Wang(a), Hung-Duen Yang(b),

Jeffrey W. Lynn(c), and Helmuth Berger(d)

(a)Department of Physics, National Central University, Jhongli 32001, Taiwan Email:whli@phy.ncu.edu.tw

(b)Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (c)NIST Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA

(d)Institute of Physics of Complex Matter, EPFL, Lausanne, Switzerland

Ferroelectricity is a physical phenomenon where spontaneous electrical polarization P appears below a certain temperature TC. Ferroelectric order can arise in a number of ways, such as from a structural change, a spin-exchange interaction, or spin-orbit interaction that triggers relative displacements of the positive and negative ions. Multiferroics, where both ferroelectric and magnetic order coexist, are quite uncommon, but are of particular interest both in understanding the fundamental interactions between the two types of order and in the developing devices for practical applications. For conventional (type-I, or proper) ferroelectrics the two types of order must be associated with different atoms, with generally a weak interaction between the two order parameters. For type-II (improper) ferroelectrics, on the other hand, the ferroelectric displacements originate from some other type of ordering, and of particular interest here, are when this is magnetic order. The novel metal tellurates M3TeO6, where M is a first-row transition metal, have been shown to be rich in crystalline chemistry. Ferroelectricity, ferromagnetic and antiferromagnetic spin orders, complex incommensurate (ICM) spin structures, and magnetic-field-driven polarization have all been observed. Here, we report on the observations of a strong interplay between the order parameters of ferroelectricity and both commensurate and incommensurate magnetic order in single crystal cobalt tellurate Co3TeO6. We find Co3TeO6 to be a type-II multiferroic. Long range ICM magnetic order develops below TM1=26 K, which is followed by two additional zero-field phase transitions at TM2=19.5 K and TM3=18 K, where commensurate order and ferroelectricity develop, respectively. We demonstrate directly that the intensity map of the k-l scattering plane excludes having commensurate (CM) order at the (0 1/2 1/4) wave vector, suggested in a report based on the results from a powder sample. Polarized neutrons have also been used to confirm that the observed high order ICM reflections are magnetic in nature and the magnetic structure contributes no intensity to the (600) reflection even at base temperature. Contributions from the Te ions at the crystallographic 8f sites to ferroelectric transition are also found, where a significant amount of electric charges shifts from the Te ions to their neighboring Co and O ions upon cooling through the ferroelectric transition.

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CC-04

Orbital ordering as the unifying mechanism for both the structural and antiferromagnetic transitions in the

Fe-based superconductors

Wei Bao

Renmin University of China, Department of Physics

Email: * wbao@ruc.edu.cn The breaking of the four-fold crystalline symmetry in the parent compounds

of the 1111, 122 and 11 families of the Fe-based superconductor has generated active current interest in the origin of the structural and magnetic transitions which renders a two-fold crystalline symmetry. A spontaneous symmetry breaking of a Fermi liquid in the form of a nematic phase has been proposed and received a lot of attention. We have investigated both the structural and antiferromagnetic transitions in 1111, 122, 11 and 245 families of the Fe-based superconductors using the capacity of neutron scattering in simultaneous measurements of the structural and magnetic orders [1-4]. The close relation between the expansion or contraction of the Fe pair distance with the antiferromagnetic or ferromagnetic exchange interaction [1-4] is very similar to our previous experience in investigations on classic transition metal oxides [5,6] for which such a close relation is shown to be a manifest of an underlying orbital order transition. Orbital ordering was initially invoked by Goodenough to explain rich magnetic phases discovered by Wolland and Koehler in their classic neutron scattering study on perovskite Manganites [7]. It is an indication of strong coupling between structural, magnetic and orbital degrees of freedom in transition metal compounds. Our neutron scattering works show that all three types of antiferromagnetic structures discovered so far in the Fe-based superconductors [1-4] can be attributed to two types of Fe bonds : contracting and ferromagnetic bond, and expanding and antiferromagnetic bond [8,1-4]. We attribute their difference in the different occupancy of the dxz and dyz orbitals as early as in 2008 [1]. Such an orbital ordering scheme can consistently explain all occurrences of the structural and magnetic transitions in 1111, 122, 11 and 245 families of Fe-based superconductors [8-10]. Therefore, the dxz/dyz orbital ordering is the essential physics process in the Fe-based superconductors, and the breaking of the four-fold symmetry of these compounds is a naturally expected consequnce of the orbital ordering.

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CC-05

Study of the magnetism of the functional materials

using neutron and x-ray scattering

Chao-Hung Du Department of Physics, Tamkang University, Taiwan

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CC-06

Investigating magnetic and multiferroic oxide thin films with quantum beam techniques

Sara J. Callori(a) (a)Department of Physics, California State University, San Bernardino, California,

USA e-mail: sara.callori@csusb.edu

Thin films of complex oxides show great promise for a wide range of functional

properties, including magnetism and multiferroic behaviour, which can be induced and

tuned by a careful choice of parameters such as epitaxial strain, stoichiometry, sample

geometry (e.g. through artificial heterostructures), and applied electric and magnetic

fields. Quantum beam techniques, such as neutron and x-ray scattering, have proven to

be powerful tools to study these materials. These techniques are capable of resolving

structural and magnetic information, often in the same measurement, as well as

uncovering correlations between those two properties in a single measurement.

This talk will focus on the application of quantum beam techniques to functional

perovskite oxide thin films and multilayers. Several techniques relevant to studying

structural and magnetic properties will be reviewed, including x-ray and neutron

diffraction and reflectometry and x-ray dichroism. Recent experimental results will be

used to demonstrate the utility of each technique as applied to magnetic oxide thin

films and multilayers. Examples will include work on the multiferroic material BiFeO3,

including the application of diffraction techniques to observe spin structures and

resonant x-ray scattering to perform element specific profile across the

BiFeO3/La0.67Sr0.33MnO3 interface [1]. The utility of quantum beam measurements in

the search for new multiferroic materials will also be discussed, with a focus on recent

results on SrCoO3-δ thin films [2]. Finally, time resolved measurements will be

highlighted, which offer possibilities to characterize oxide thin films on the nanoscale

[3] or during sample growth [4]. [1] J. Bertinshaw, et al., Physical Review B, 90, 041113(R) (2014). [2] S.J. Callori, et al., Physical Review B, 91, 140405(R) (2015). [3] M.P. Cosgriff, et al., Advanced Electronic Materials, 2, 1500204 (2016). [4] B. Bein, et al., Nature Communications, 6, 10136 (2015).

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PG-01

Preparation and magnetic properties of perpendicular Co-rich Co-Pt films

S. C. Chen (a), C. F. Lu(a), C. K. Wen(b), T. H. Chuang(b), S. T. Chen(b), P. C. Kuo(b)

(a) Department of Materials Engineering and Center for Thin Film Technologies

and Applications, Ming Chi University of Technology, New Taipei 24301, Taiwan. (b) Institute of Materials Science and Engineering, National Taiwan University,

Taipei 10617, Taiwan. e-mail: chensc@mail.mcut.edu.tw

Materials having high magnetocrystalline anisotropy constant (Ku) are generally desirable for high density magnetic recording applications due to their thermal stability even with smaller grain size. The Ku of hcp Co3Pt alloy films is as high as 2x107erg/cm3, and the temperature required for obtaining high perpendicular magnetic properties is relatively low at 300 °C. Therefore, Co3Pt alloy films have significant potential to be utilized in ultra-high density (1Tb/in2) magnetic recording media. It has been reported that Co-rich Co-Pt films with perpendicular magnetic properties can be achieved by introducing a Pt underlayer or Ru/Pt bilayers. The lattice parameter of Ag is close to Pt and both structures are fcc. Furthermore, compared to a Pt underlayer, the Ag does not change the composition ratio of Co to Pt in the Co3Pt magnetic layer, and the cost of Ag is much lower than that of Pt.

In this study, Co80Pt20 films were deposited onto Ru/Ag bilayer films. The perpendicular magnetic anisotropy was achieved by depositing a Co80Pt20 film onto Ru/Ag bilayer films using an argon working pressure of 3 mTorr to sputter the Ru layer at ambient temperature. Its perpendicular coercivity and perpendicular squareness are 3980 Oe and 0.76, respectively. When the working pressure increases to above 10 mTorr, the perpendicular magnetic anisotropy of the films deteriorates greatly. However, as shown in Fig. 1 (a) and (b), both perpendicular coercivity and perpendicular squareness of the films can be increased to 4530 Oe and 0.82 respectively if the Co80Pt20 film is deposited on a higher texture Ru(0002)/Ag(111) bilayer that has been annealed at 300 °C. When this Co80Pt20/Ru/Ag multilayer film is subsequently post-annealed at 300 °C, the perpendicular magnetic properties are improved further. The perpendicular coercivity and perpendicular squareness of the films are further increased to 5040 Oe and 0.87 respectively, which reveal its significant potential as perpendicular magnetic recording media for ultra-high density recording.

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Fig. 1. In-plane and perpendicular magnetization curves of (a) Co80Pt20(25 nm) deposited onto Ru(30 nm)/Ag(100 nm) bilayer films that have been annealed at 300 °C and (b) Co80Pt20(25 nm)/Ru(30 nm)/Ag(100 nm) multilayer films post-annealed at 300 °C.

(a) (b)

B-130

PG-02

Epitaxial Co80Pt20 films with columnar grains and

perpendicular magnetic anisotropy at ambient temperature

S. C. Chen(a), C. F. Lu(a), R. Z. Chen(b), C. M. Wang(c), P. C. Kuo(c)

(a) Department of Materials Engineering and Center for Thin Film Technologies

and Applications, Ming Chi University of Technology, Taipei 243, Taiwan. (b) New Materials R&D Dept., China Steel Corporation, Kaohsiung 812, Taiwan.

(c) Institute of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan.

e-mail: chensc@mail.mcut.edu.tw

Ordered Co3Pt film is a promising material for high density recording media, due to its magnetocrystalline anisotropy constant being higher than that of current CoCrPt recording materials by a factor of around 10 times. Furthermore, the manufacturing temperature of Co3Pt used for obtaining high perpendicular magnetic properties is similar to that used in current hard disk manufacture. However, single-layered Co3Pt films incline towards in-plane magnetic anisotropy or random orientation [1], which cannot be utilized in perpendicular magnetic recording applications. It has been reported that Co-rich Co-Pt films with high perpendicular magnetic properties can be achieved by introducing a Pt underlayer [2] or Ru/Pt bilayer [3]. However, the expensive Pt layer in the films would result in excessively high cost.

In this study, the magnetic anisotropy of single-layered Co80Pt20 film with thickness of 50 nm deposited directly on glass substrates at ambient temperature inclines towards random orientation. It tends to in-plane magnetic anisotropy through the introduction of a (1011) texture, 30 nm Ru layer under the Co80Pt20 film. The perpendicular magnetic anisotropy can be increased slightly by inserting a 100 nm thick Cu layer between the Co80Pt20 and Ru layers. However, when the Cu layer is introduced under the Co80Pt20/Ru bilayer films, the magnetic anisotropy becomes perpendicular. This is because a fcc Cu (111) underlayer can promote a hcp Ru (0002) seed layer to induce (0002) texture in hcp Co80Pt20 magnetic layer, leading to a good perpendicular magnetic anisotropy in the Co80Pt20 films. It is found that columnar Co-rich Co-Pt nano-grains with perpendicular coercivity of 4580 Oe and perpendicular squareness of 0.77 can be achieved by depositing Co80Pt20(50 nm) film onto Ru(30 nm)/Cu(100 nm) bilayer films at ambient temperature. This Co80Pt20 film is a promising candidate for perpendicular magnetic recording media applications.

[1]Y. S. Chen, An-Cheng Sun, H. Y. Lee, Hsi-Chuan Lu, Sea-Fue Wang, Puneet Sharma, J. Magn. Magn. Mater., 391, 12 (2015). [2] S. Mifuji, H. Sakuma and K. Ishii, J. Appl. Phys., 97, 10N102 (2005). [3] T. Shimatsu, H. Sato, Y. Okazaki, H. Aoi, H. Muraoka, Y. Nakamura, S. Okamoto and O. Kitakami, J. Appl. Phys., 99, 08G908 (2006).

B-131

PG-03

MAMR frequency selection on [CoX/Pt]4 media with

different anisotropy orientation distribution Zhen Zhao, Jiangnan Li, Longze Wang, Dan Wei*

Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084

Microwave assisted magnetic recording (MAMR) technology, with microwave generated by the spin transfer oscillator (STO), has potential in future magnetic recording. In a single particle, the microwave field assists the switching around the ferromagnetic resonant (FMR) frequency. In this work, the frequency selection for SNR gain will be studied in (CoX/Pt)4 media.

The micromagnetic model of (CoX/Pt)4 media is built upon a regular mesh with the Voronoi polycrystalline structure included, and the thermal stability requirement is satisfied [1]. Two different perpendicular anisotropy orientation distributions are used with same average interfacial anisotropy field Hk=24.3kOe: in Model A, with an orientation distribution of exp(-αθsin2θ) (αθ=20); in Model B, the interfacial anisotropy is modeled by a sum of two terms: a vertical 7 kOe term plus another uniaxial term following an orientation distribution exp(-αθsin2θ) (αθ=6). Other media magnetic parameters and recording parameters are set in accord with Ref [1-2]. The anisotropy of each layer has been optimized (listed in the table) for a better write performance.

The media SNR gain for MAMR has been shown in Fig. 1 for model A and B respectively. In Model A, 4dB SNR gain has been found between 18 GHz and 28 GHz; and in model B, similar SNR-f relationship has been found, with 2.5 dB gain and a 1dB fluctuation. This characteristic is totally different from that on the (CoX/Pt)1 monolayer model, which has a certain SNR fluctuation period (about 5GHz) and a narrow optimized frequency range (<4 GHz) near each peak. The anisotropy field and the write head field varying in the each layer of media cause a larger resonant frequency range [3]. The comparison of the two models demonstrates that more uniform anisotropy orientation is beneficial for more stable SNR gain at different frequency.

This work is supported by ASTC project.

Fig 1: SNR changed as function of ac field frequency with different media anisotropy distributions.

[1] J. Li, Z. Zhao, L. Wang, M. Zhang, D. Wei, 2016JointMMM -Intermag Conference, CV-13.

[2] Z. Zhao, J. Li, L. Wang, D. Wei, K.Z. Gao,IEEE Trans.

Magn., 51(11),3202204 (2015). [3] L. Lu, M. Wu, M. Mallary, G. Bertero, K. Srinivasan,

R. Acharya, H. Schulthei, A. Hoffmann, Appl. Phys. Lett., 103, 042413 (2013).

Anisotropy Energy Density in (CoX/Pt)4: K1-K2-K3-K4(107 erg/cm3) of Each CoX

Layer Model A 1.55-1.48-1.42-1.35 Model B

( ith H ’ 7 kO )1.17-1.10-1.04-0.96

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PG-04

ECL2 thickness

Hc Angular Dependence of ECC Media for Ontrack and Crosstrack Performance

Justin Hwu, Pin-Wei Huang*, Shifu Lee, and Weikang Shen

Seagate Technology, Fremont, CA, USA *Email: pin-wei.huang@seagate.com

Exchange coupled composite (ECC) media structure together with a

continuous-granular-composite (CGC) layer as cap layer, is the dominant media structure for nowadays product in hard disk drive (HDD) industry. The current ECC media structure used in industry is much more complicated than that of originally proposed [1-2], and the analysis has also become a lot difficult. In this work, the media structure under study is composed of two magnetic granular layers (M1 and M2), two exchange control layers (ECL1 and ECL2), and one CGC layer. The media stack profile is M1/ECL1/M2/ECL2/CGC. It is observed that adjusting the thicknesses of ECL1 and ECL2 can result in different recording performances. Increasing ECL1 thickness can result in higher linear density but lower track density, which is a trade-off situation that is commonly encountered in designing media structure. In contrast, increasing ECL2 thickness, however, can result in better linear density and better track density simultaneously (Fig. 1). Micromagnetic simulation and magneto-optic Kerr effect (MOKE) microscopy for the hysteresis loops at different field angles are conducted to understand such phenomenon. It is concluded that the different angular dependences of the magnetic coercivity by varying ECL1 and ECL2 respectively is the main cause of the different recording performances that are observed. A media design guideline based on this understanding is also proposed.

[1] R. H. Victora and X. Shen, “Composite media for perpendicular magnetic

recording,” IEEE Trans. Magn., vol. 41, no. 2, pp. 537-542, Feb. 2005.

[2] J. P. Wang, W. Shen, and J. Bai, “Exchange coupled composite media for

perpendicular magnetic recording,” IEEE Trans. Magn., vol. 41, no. 10, pp. 3181-3186,

Oct. 2005.

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Fig. 1 M-H loops of CoPt-B2O3 granular media with dmag: 4-16 nm. An inset shows the in-plane view TEM.

-20 -10 10 20

-0.5

0.5

0

H (kOe)

m (x10-3 emu)

20nm

dmag (nm): 16

1284

dmag: 16 nm

CoPt-B2O3 granular media with high Ku and low intergranular exchange coupling

Kim Kong Tham(a), Ryosuke Kushibiki(a), Shintaro Hinata(b), Shin Saito(b)

(a) Tanaka Kikinzoku Kogyo K. K., 22, Wadai, Tsukuba, Ibaraki, 300-4247, Japan (b) Tohoku University, 6-6-05, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

e-mail: tham@ecei.tohoku.ac.jp

CoPt-oxide granular media have been widely used for the perpendicular recording.

To further extend the recording density, the increase of thermal stability through the

enhancement of uniaxial magnetocrystalline anisotropy of the magnetic grains (Kugrain)

while maintaining low intergranular exchange coupling between grains is essential. It

can be achieved by realizing the phase separation between grains and the grain

boundaries material. Many authors have proposed various oxides for the grain

boundaries material. However, for some oxides, Kugrain will be degraded to much lower

than CoPt alloy. In this paper, we discuss the effect of utilizing B2O3 and the guideline

of choosing the oxides from the aspect of magnetic properties and microstructure.

Fig.1 shows M-H loops of CoPt-B2O3 granular media with thickness (dmag): 4-16 nm

deposited on Glass/Ta(5 nm)/Pt(6 nm)/Ru(20 nm). An inset shows an in-plane view

TEM of the medium. For dmag: 16 nm, coercivity (Hc) and nucleation field (Hn) are 8.0

and 1.6 kOe, respectively, slope of M-H loop at around Hc (α) is relatively small of 1.5.

Hc and Hn of the CoPt-B2O3 medium are higher than those of other medium [1]. Kugrain

of the medium with exclusion of oxide is 1.1×107 erg/cm3. It is quite close to that of

CoPt alloy [2]. This reveals that metal magnetic grains and oxides in the medium are

phase separated and intergranular exchange

coupling between grains is quite low. In the

TEM image, each magnetic grain is well

isolated with B2O3 grain boundaries, which

corresponds to small α. Furthermore, the

average grain size is 6.5 nm which is

smaller than typical perpendicular recording

media (8-9 nm). The result suggests that

B2O3 is a promising boundary material.

[1] J. Ariake et al., IEEE Trans. Magn., 41,

3142 (2005). [2] N. Nozawa et al., IEEE

Tran. Magn., 49, 3596 (2013).

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PG-06

=-

Stacking faults induced domain wall pinning in (001) FePd thin film

Ching Hung Hsiao(a), Chuenhou (Hao) Ouyang (a)

(a) Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan e-mail: houyang@mx.nthu.edu.tw

FePd (001) films, prepared by an electron beam deposition system on MgO(100), exhibit a perpendicular magnetic anisotropy (1.7107 erg/cc) with a high order parameter (0.92). The strain relaxation process in epitaxially grown thin-film is pretty common [1] and the strain relaxed induced defects were detailed analysed by high resolution transmission electron microscope(HRTEM), as shown in Fig. 1(a)-(c). The relation between stacking faults induced by the strain relaxation, which act as strong domain wall pinning sites, and perpendicular coercivity(Hc,) of FePd films prepared at 400-700oC have been investigated. The variation of Hc is shown in Fig. 1(d). Hc, can be enhanced via raising the stacking fault densities, which can be promoted by climbing dissociation [2]. The increased stacking fault densities with large Hc, (6kOe) is obtained for samples prepared at 650 oC. On the other hand, Hc, drops significantly prepared at 700oC and treated with post-annealing at 700oC for 5hs, resulting from reducing stacking fault density. This result suggests the coercivity can be manipulated via controlling stacking fault density in FePd film, which may pave a way for future magnetic devices. Fig. 1 [Fe 3Å/Pd 4Å]5 deposited at 650oC:(a)cross-sectional HRTEM image, (b) IFFT and FFT image of red rectangular and inserted with multislice simulation image(MSI), and (c)HAADF image inserted with MSI.(d)M-H loops of [Fe 3Å/Pd 4Å]5 prepared at 400,650 and 700oC treated with post annealing.(⊥ and //: out-of-plane and in-plane loop) [1] J. P. Attané et al., Applied Physics Letters 79, 794 (2001). [2] C. H. Hsiao et al., Applied Physics Letters 107, 142407 (2015).

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PG-07

Numerical analysis on cross-track characteristics for tracks recorded with microwave assistance

T. Tanaka(a), D. Sakamoto(a), Y. Kanai(b) and K. Matsuyama(a)

(a)ISEE, Kyushu University, Fukuoka, Japan (b) IEE, Niigata Institute of Technology, Kashiwazaki, Niigata, Japan

e-mail: t-tanaka@ed.kyushu-u.ac.jp

Several methods including energy assisted magnetic recording schemes have been

proposed for solving the writability problems in magnetic recording. In these recording

schemes, microwave-assisted magnetic recording[1] has recently attracted much

attention for future ultra-high density recording. The effects of microwave assistance

for the magnetization reversals closely relate with magnetic resonance phenomena

which is strongly affected by damping constant of recording layer. In this study,

recording performance was numerically estimated using micromagnetic simulations

through signal to noise ratios (SNR) assuming an exchange-coupled composite (ECC)

structured medium and cross-track SNRs were profiled. A 30-nm-track-wide

asymmetric structured recording head with a spin torque oscillator designed for

shingled magnetic recording was employed for recording simulation and a

17-nm-track-wide MR sensor was assumed in the reading processes. Hk and Ms for the

soft section of the ECC medium are 17.5 kOe and 850 emu/cc, and those for the hard

section are 80 kOe and 650 emu/cc. The damping constant of the hard section is set to

0.2. Figure 1 shows cross-track profile of the SNRs as a function of damping constant

of the soft section. Microwave frequencies have

been preliminary optimized for corresponding

damping constant. Asymmetric profiles come

from the asymmetric head field distributions

and the highest SNRs are obtained at around +5

nm in the off-track position for any damping

constants. The result also shows the highest

SNRs tend to slightly increase with the

damping constant of the soft section. [1] J-G. Zhu，X. Zhu, and Y. Tang, IEEE Trans Magn., 44, 125, (2008).

-20 -10 0 10 200

5

10

15

20

25

Offtrack [nm]

SNR

[dB

]

R( f =26 GHz, =0.05)R( f =23 GHz, =0.10)R( f =22 GHz, =0.15)R( f =20 GHz, =0.20)R( f =20 GHz, =0.25)

Fig. 1 Cross-track profile of SNR as a function of damping constant.

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PG-08

The non-local energy dissipation in All-Optical magnetization Switching of GdFeCo thin films

Hiroki Yoshikawa(a), Souliman El Moussaoui(b), Shinnosuke Terashita(a), Ryohei Ueda(a), Arata Tsukamoto(b)

(a) Graduate School of Science and Technology, Nihon University, Chiba, Japan

(b) College of Science and Technology, Nihon University, Chiba, Japan e-mail: yoshikawa_hiroki@inl.ecs.cst.nihon-u.ac.jp

Clarifying the relation between All-Optical magnetization switching (AOS) [1] and the non-local energy dissipation process, we focus on the contribution from energy dissipation process on depth direction. For this purpose, we research the differently designed structure dependency of created magnetic domain. Its dependency is observed from the reversal phenomena, AOS or the multi-domains by Thermo-Magnetic Nucleation (TMN) in GdFeCo multi-layer thin films. We obserbed these phenomena that is excited by a femtosecond laser pulse on the multilayer : following the stack design hereafter: SiN (60 nm) / Gdx(Fe87.5Co12.5)100-x (l) / SiN (m) / AlTi (n) / glass sub., (where x is the Gd atomic percent and the l, m, n indexes are the thickness in nm of the respective layer (l = 10 ~30 nm, m = 5 or 0 nm, n = 10 or 0 nm) with a polarizing microscope. And l is designed around penetration depth.

From this obserbation, TMN depends on the shared absorbed energy in all the continuous metallic volume. On the other hand, AOS critically depends on the absorbed energy, too. Furthermore, laser fluence dependency of AOS created domain sizes indicate irradiated fluence threshold per magnetic domain volume Ftv is almost constant. But, lower laser irradiation around 1 ~ 2mW has large and drastic thickness dependency of it. This result is the proof of existance, the non-local energy dissipation process of electron systems in GdFeCo thin film from the incident surface into the depth direction during few picoseconds. AOS depends on the ultrafast magnetization dynamics [1] and overcome the threshold in locally absrobed energy [2]. In lower laser irradiation, lowering the energy density by dissipation sensitivelly cause decrease of swichable area, then it makes effectively increase the index Ftv.

Acknowledgement: This work was partially supported by MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2013-2017 and MEXT-Supported Grant-in-Aid for Scientific Research on Innovative Area, “Nano-Spin Conversion Science” (Grant No.26103004). References: [1] T. A. Ostler, J. Barker, R. F. L. Evans, R. W. Chantrell, U. Atxitia, O. Chubykalo-Feseko, S. El. Moussaoui, L. Le Guyader, E. Mengotti, L. J. Heyderman, F. Nolting, A. Tsukamoto, A. Itoh, D. Afanasiev, B.A. Ivanov, A.M.Kalashinikova, K. Vahaplar, A. Kirilyuk, Th. Rasing and A. V. Kimel: Nature Comm, 1666, 3:666 (2012). [2] H. Yoshikawa, S. Kogure, S. Toriumi, T. Sato, A. Tsukamoto, and A. Itoh: J. Magn. Soc. Jpn., 38, 139 (2014).

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PG-09

All-Optical magnetization Switching on multi level GdFeCo magnetic double layered film

Shinnosuke Terashita(a), Hiroki Yoshikawa(a) and Arata Tsukamo(b) (aGraduate School of Science and Technology, Nihon University, Funabashi, Japan.

(b)College of Science and Technology, Nihon University, Funabashi, Japan. e-mail : terashita_shinnosuke@inl.ecs.cst.nihon-u.ac.jp

All-Optical magnetization Switching (AOS) is triggered by ultra-short light-matter

interaction that is much shorter time scale than conventional magnetic field driven magnetic recording method[1]. The switching “on” and “off” strongly depends on absorbed energy and its fluence. In addition, the switching mechanism is differently based on sub-ps energy dissipation process in material[2]. So we can expect considerable rapid magnetic recording with AOS. Furthermore we can anticipate that AOS allows as a new type of multi-value magnetic recording without external magnetic field. In this report we irradiated a single femtosecond laser pulse to the double layered film and observed the magneto-optical image of the created magnetic domains. We designed the film structure which have GdFeCo double layer with dielectric interlayer: SiN (60 nm) / LayerⅠ:Gd27Fe63.9Co9.1 (10 nm) / SiN (5 nm) / LayerⅡ:Gd22Fe68.2Co9.8 (10 nm) / SiN (5 nm) / AlTi (10 nm) / glass sub. Dielectric SiN interlayer decouple magnetic exchange interaction and electric conduction between two metallic GdFeCo magnetic layers. This double layered film shows 4 level magnetization state and Faraday rotation signals. We found that the different state transition diagram in double magnetic layer can realise compared with magnetic field driven magnetic transition diagram. After irradiation of single femtosecond laser pulse, just the magnetization of LayerⅠ reversed in spite of it have much higher coercivity than LayerⅡ. In addition, we irradiated higher intense laser pulse to the sample. Fig.1 shows the magneto-optical image of the created magnetic domain and area profile of the image. This result shows three magnetic state was simultaneously created following Gaussian intensity profile of irradiated laser pulse. Acknowledgments This work is partially supported by MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2013-2017 and MEXT-Supported Grant-in-Aid for Scientific Research on Innovative Areas, “Nano-Spin Conversion Science” (Grant No.26103004). References [1] C. D. Stanciu, et.al. : Phys. Rev. Lett. 99, 047601 (2007). [2] H. Yoshikawa, et.al. : J. Magn. Soc. Jpn. 38, 139(2014).

Fig.1 The magneto-optical image of

the created magnetic domain and

area profile of the image.

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Magnetic properties and spin dependent transport in Fe-filled carbon nanotubes

Y. H. Xu, Z. W. Zhang, F. Boi, T. Yu*

College of Physical Science and Technology, Sichuan University, Chengdu 610064, China

e-mail: work_tian@scu.edu.cn

Recently, carbon nanotubes with foreign materials filled in their cavity or coated on the tube surface have attracted much attention and, among various materials, transition metals are of particular interest, because one-dimensional nanowires produced inside or outside the tube can be ferromagnetic and directly used for, for example, spin polarized transport devices or magnetic storage [1-3]. In this paper, we report synthesis of ordered Fe-filled carbon nanotube (Fe-CNT) with length of a few hundreds micrometre by using Cl-assisted chemical vapour deposition. The magnetic, electrical, and spin dependent transport properties of samples are investigated from room temperature to 5 K. Large saturation magnetization and square magnetic hysteresis loop are observed, suggesting high quality growth of Fe inside the CNT capsule, which is further confirmed by XRD and TEM characterization. Magnetoresistance was successfully measured in Au/CNT-Fe/Au sandwich structure by applying current along Fe-CNT axial direction. As shown in Fig. 1, normal magnetoresistance loop is obtained and the magnetoresistance ration (MR) is enhanced with lowering temperature. Combining with magnetization ZFC-FC measurements, it is concluded that the spin dependent transport is dominated by scatting from Fe inside CNT capsule.

This work was supported by the National Natural Science Foundation of China [NSFC, Grant No. 11504249] and the Youth Foundation of Sichuan University.

[1] M.S. Dresselhaus, G. Dresselhaus, J.C. Charlier and E. Hernandez, “Electronic, thermal and mechanical properties of carbon nanotubes”,Philos. Trans. R. Soc., A 362 (2004) 2065–2098. [2] M.M.J. Treacy, T.W. Ebbesen, J.M. Gibson, “Exceptionally high Young's modulus observed for individual carbon nanotubes”, Nature, 381 (1996) 678–680. [3] S. Karmakar, et al., “Magnetic behavior of iron-filled multiwalled carbon nanotubes”, Journal of Applied Physics, 97, 054306 (2005).

Fig.1 Temperature dependence of magnetoresistance ration (MR).The insert shows magnetic field dependence of resistance under 5K.

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PH-02

Construction of Pulse Laser Deposition System for fabrication of magnetic multilayers

M. Kotsugi, M. Tomita, J. Ochiai

Tokyo University of Science, 6-3-1 Niijuku, Katsushika, Tokyo, Japan e-mail: kotsugi@rs.tus.ac.jp

Magnetic multilayer has been the source of wide spread applications such as

magnetic random access memory and rare-metal-free permanent magnet [1,2]. The surface and interface structure play a key role in the emergence of curious physical property. Pulse laser deposition (PLD) is a powerful technique to fabricate thinfilms and multilayers [3]. It has ultrahigh instantaneous deposition rate by using laser ablation of target materials, and it show almost ideal layer-by-layer morphology with high nucleation density. Morphology of deposited surface is smoother than traditional molecular beam epitaxy. PLD provides great opportunities to design artificial multilayer structure that show promising physical properties. Here, we report the construction of pulse laser deposition system for the fabrication of magnetic multilayer systems. We utilized Nd:YAG laser by LOTIS TII with the wave length of 266 nm. Deposition can be carried out in ultra high vacuum chamber. 6 target materials can be installed in the chamber and exchanged without breaking vacuum (Fig.1). We evaluated deposition rate of various targets (Fe, Co, Cu) on Cu(001) surface. Clear RHEED pattern and oscillation was confirmed, and deposition rate was evaluated from the period of RHEED oscillation. Deposition rate was instable, even if pumping energy was fixed. Then, we evaluated the deposition rate as a function of laser power just before ablation. We could obtain standard curve of deposition rate of Fe, Co, Cu respect to laser power (Fig.2). This standard curve is helpful to suppresses laser power dependence and stabilize deposition rate with the accuracy of 8%. [1] M. Kotsugi et al. JMMM 326 (2013) 235 [2] T. Kojima et al. J. Phys. Cond. Matt. 26 (2014) 064207 [3] J. Shen et al. Surf. Sci. Rep. 52 (2004) 163

YAG laser

Sh e ied ing b ox

Sa m p le s ta ge

Ta rge t s ta ge

TMP RHEED gun

RHEED Screen

Fig.1 Pulse laser deposition system

Fig.2 Standard curve of deposition rate of

Fe, Co and Cu as a variation of laser

power

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PH-03

Insertion Effect of Nonmagnetic Spacer in Co/FeMn

Exchange Bias Films

A. Yoshida, N. Hosoito

Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Japan

e-mail: y-akihiro@ms.naist.jp

Insertion of nonmagnetic spacer layer in magnetic thin film allows us to drastically change its magnetic property from bulk characteristics. First such systems were investigated in ferromagnetic (FM)/spacer/FM structures. By varying the spacer thickness, it was discovered that the coupling between FM layers could be changed from FM to antiferromagnetic (AFM) layer. However, it is not clear that how to relate the strength of EB to the spacer thickness and material. Here, we have investigated the relationship between the strength of EB and induced magnetization in spacer layer in FM/spacer/AFM. The samples were prepared by sputtering. The sample structures are Si substrate/Ta(10 nm)/Ru(10 nm)/Co(4 nm)/Cu(tCu nm)/FeMn(7 nm)/Ta(2 nm). The Cu thickness was varied from 0 to 1.5 nm. After the deposition, all samples were annealed in 1 kOe magnetic field at 200 °C for 1 hour. We confirmed that the film has (111) orientation by X-ray diffraction. The exchange bias was examined from magnetization curve measurements with a vibrating sample magnetometer. Figure 1 (a) shows the magnetization curve of Co/Cu/FeMn. Figure 1 (b) shows Cu thickness dependence of the strength of exchange bias (Hex) and coercivity (Hc). There is almost no change in Hc, whereas Hex obviously changes. This result suggests the tendency of Hex was caused by the distribution of induced moment of Cu layer[1].

[1] S. Uegaki, A. Yoshida, and N. Hosoito, Journal of the Physical Society of Japan 84, 034704 (2015).

Figure 1 (a) Magnetization curve of Co/Cu/FeMn (b) Cu thickness

dependence of the strength of exchange bias and coercivity.

-180 -120 -60 0 60 120 180

-0.001

0

0.001

H (Oe)

M (

emu)

tCu

= 0.6 nm 0°direction

90°direction

(a)

0 0.4 0.8 1.2 1.60

20

40

60

80

100

Hex

, Hc

(Oe)

Cu thickness (nm)

Hex

Hc

(b)

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PH-04

Paramagnetic gadolinium-doped zinc oxide thin films grown under two different oxygen partial pressure

Fang-Yuh Lo(a), Tsung-Chun Hsieh(a), Tzu-Lung Tseng(a), Xiu-Zhi Mi(a), Chih-Feng Chien(a), Yung-Yuan Hsu(a), and Ming-Yau Chern(b)

(a) Department of Physics, National Taiwan Normal University, 11677 Taipei City,

Taiwan (b) Department of Physics, National Taiwan University, 10617 Taipei City, Taiwan

e-mail: fangyuhlo@ntnu.edu.tw

Gadolinium(Gd)-doped zinc oxide (Gd:ZnO) thin films were fabricated on c-oriented sapphire substrate under two different oxygen partial pressure (8×10-2 and 3×10-1 mbar) by pulsed-laser deposition with doping concentration ranging from 1 to 20 atomic percent. Structural, optical, and magnetic properties of Gd:ZnO thin films were studied.

X-ray diffraction (XRD) revealed incorporation of Gd into ZnO host matrix without secondary phase, where the diffraction peak of the thin film can be observed up to 15 atomic percent.

Defects identified by photoluminescence (PL) spectroscopy were zinc vacancies and zinc interstitials for thin films grown under both oxygen partial pressure, where oxygen interstitial were additionally identified from thin films grown under 8×10-2 mbar of oxygen partial pressure.

Magnetic investigations with a superconducting quantum interference device (SQUID) showed paramagnetism without long-range order for all Gd:ZnO thin films. From our investigations, Gd:ZnO thin films could be useful for spin alignment and magneto-optical applications.

Figure 1 Magnetization loops of Gd-doped ZnO measured at T = 5 K.

-40000 -20000 0 20000 40000-800

-600

-400

-200

0

200

400

600

800

Mom

ent

(em

u)

Magnetic Field (Oe)

T = 5 (K) / PO2

= 3×10-1(mbar)

0% 3% 5% 10%

-40000 -20000 0 20000 40000-600

-300

0

300

600

Mom

ent

(em

u)

Magnetic Field (Oe)

T = 5 (K) / PO2

= 8×10-2(mbar)

0% 3% 5% 10%

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PH-05

Gate-voltage Controlled Tunneling Magnetoresistance in a Magnetic Tunneling Junction with an Inserted Thin

Metallic Layer

Sui-Pin Chen

Department of Electrophysics, National Chiayi University, Chia Yi, Taiwan e-mail: spchen@mail.ncyu.edu.tw

Magnetic tunneling junctions (MTJs) continue to receive considerable attention because of their large tunneling magnetoresistance (TMR) effect not only for the depth of fundamental phenomena available, but also for the potential and proven applications [1]-[4]. An MTJ consists of an FM1-I3-FM4 structure, where FM1 and FM4 are ferromagnetic electrodes and I3 is a thin insulator. The TMR effect originates from spin-dependent tunneling (SDT) in a MTJ. The change of SDT in the MTJ is measured by the TMR ratio. In the FM1-I3-FM4 MTJ, SDT is extremely sensitive to the interface structures between the insulator and each electrode. Thus, modulating one of the interfaces can change the TMR. One way to achieve this is to insert a thin nonmagnetic metallic layer (M2) between one of the ferromagnetic electrodes, FM1 or FM4, and the insulator I3. The M2-inserted MTJ is the FM1-M2-I3-FM4 structure. The inserted M2 layer leads to a severe alteration of the M2-I3 interface, thus resulting in a dramatic effect on SDT and the TMR ratio. The excellent experimental work of Yuasa et al. shows how the TMR is affected by the inserted Cu metal in a high-quality Co-Cu-Al2O3-NiFe MTJ [1]. A distinct attenuated oscillation of the TMR ratios with increasing the Cu thickness is observed at room temperature when the inserted Cu thickness is less than to 29Å. Here, we propose a method of changing the M2-I3 interface. The proposed method uses a gate voltage on the M2 layer to alter the potential profile at the M2-I3 interface, and to modulate the TMR ratio in the FM1-M2-I3-FM4 MTJ.

[1] S. Yuasa, T. Nagahama and Y. Suzuki, Science, 297, 234 (2002).

[2] J. C. Slonczewski, Physical Review B, 39, 6995 (1989).

[3] S.-P. Chen, Journal of Applied Physics, 107, 09C716 (2010). [4] J. D. Burton and Evgeny Y. Tsymbal, Physical Review B, 93, 024419 (2016).

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Modulating permalloy thin films on grating structure for anisotropy magnetic sensor

G. H. Lai, H. C. Han ,J. C. Wu* Department of Physics, National Changhua University of education, Changhua 500,

Taiwan *e-mail: phjcwu@cc.ncue.edu.tw

Magnetoresistive effect means that the conductivity of martial will be affected by external field (Hext). Anisotropic magneto resistivity (AMR) is a kind of magneto resistivity (MR), AMR has violent variation of MR because of spin-orbital coupling effect. The effect has relation to the angle of magnetization field to current flow. The research fabricates a modulated permalloy (Py, Ni80Fe20) magnetic nanostructure using the holographic technique realized in a degenerate two-wave mixing experiment and exhibited a sinusoidal profile with a periodicity of around 1μm [1]. Thus, we use photolithography to define grating structure with a periodicity of around 3μm. Next, the grating structures are etched to various depths by reactive ion etcher (RIE). Finally, they are deposited modulating Py thin films by ion beam sputtering (Fig.1). Due to shape anisotropy, the magnetization of thin film will align to the long-axis of groove direction. Therefore, the magnetic properties of the Py thin films are affected by the groove construction. The sample with 20nm Py shows an uniaxial magnetic anisotropy with an easy and hard axis direction. When Hext is following with the groove direction (Hext at 0˚; easy axis), the magnetization switches in a clear Barkhausen jump, (Fig.2(a), black dot). For Hext is perpendicular to the groove direction (Hext at 90˚; hard axis)(Fig.2(b), red dot), with a more narrow hysteretic cycle than last one. According to the result, the thickness of Py film and the structure of sample both affect M(H) loop. We aim to complete the highly sensitive AMR sensor.

Fig. 2 Magnetic measurements of Py thin film

grating with 3μm (a)20 nm and(b)40 nm with H

is parallel and vertical to the groove direction Fig. 1 The schematic fabrication

[1] J. Berendt, J. M. Teixeira, A. García-García, M. Raposo, P. A. Ribeiro, J.

Dubowik, G. N. Kakazei, and D. S.Schmool, Appl. Phys. Lett. 104, 082408 (2014)

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PH-07

Fig. 1. Schematic of a designed nanowire with DW (a) and the Vout waveform (b).

Fig. 2. Dependence of the Vout on the xDW (a), and the comparison of the SSW profile for different DW position; xDW = 168 nm (b) and = 300 nm (c).

Controlling of standing spin wave configuration in nanowires with domain wall

X. Ya, T. Tanaka and K. Matsuyama

Graduate School of ISEE, Kyushu University, Fukuoka 819-0395, Japan e-mail: yaxiaorui@spin.ed.kyushu-u.ac.jp

Spin dynamics in nanostructured magnetic system have attracting intense research interests from view point of fundamental physics and practical applications. The geometrically confined standing spin wave resonance (SSWR) is one of the most power efficient excitation modes. Various kinds of SSWR modes have been observed in wires [1], squares [2] and rectangular dots [3], made of in-plane magnetization films. In the present study, the SSWR properties of nanowires with perpendicular anisotropy have been numerically investigated. Especially, the effect of the domain wall (DW) on the SSWR is focused, aiming at the application to a novel memory and logic applications. Fig. 1 (a) presents a designed device structure, consists of a nanowire and inductively coupled conductors for the SWs generators (GE1, GE2) and detector (DE). Material parameters of large perpendicular and low damping ferromagnets, such as MnGa, MnAl, were assumed in the micromagnetic simulations: Ms = 1000 emu/cm3, Hk = 13 kOe, = 0.01. Pulsed microwave currents with phase lag = and the duration of 930 ps (37.2 ps (=1/(26.9 GHz)) × 25 periods) were assumed to be applied through GE1 and GE2, which excite the 2nd mode SSW along the nanowire. The inductive output waveform when the DW located at the nanowire center is shown as Fig. 1(b). The maximum amplitude Vout computed for various locations of the DW (xDW) is shown in Fig. 2(a). The significant dependence of the Vout reflects the modification of the SSW configuration due to the DW location, as shown in Fig. 2(b), (c). The DW located under the GE locally suppresses the magnetization precession, reflecting lower Vout, while the influence from the DW located at the nanowire center (node of the SSW) is subtle, reflecting higher Vout. The obtained numerical results demonstrate feasibility of the domain wall location as a state variable of nanowires [1] Z. K. Wang, et al., Phys. Rev. Lett., 89, 027201 (2002). [2] A. Barman, et al., Phys.Rev. B, 69, 174426 (2004). [3] G. Carlotti, et al., J. Appl. Phys., 117, 17A316 (2015).

B-145

PH-08

Thermal Analysis of Superparamagnetic Nanoparticles Subject to an Alternating Magnetic Field

C. Y. Ho (a), B. C. Chen(b), J. W. Yu(a) , M. Y. Wen(c)

(a) Department of Mechanical Engineering, Hwa Hsia University of Technology, Taipei 235, Taiwan

(b)Department of Chinese medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi 622, Taiwan

(c) Department of Mechanical Engineering, Cheng Shiu University, Kaohsiung 833, Taiwan

e-mail: hcy2182@yahoo.com.tw

This paper presents the thermal analysis of superparamagnetic (SPM) nanoparticles used for hyperthermia of cancer tumor. Hyperthermia, heating disease sites to 42°C–45°C to cause cancer cell damage or death without harm to the normal cells or tissue, is a promising mode of adjuvant cancer therapy intended to enhance the efficacy of traditional therapies such as radiotherapy and chemotherapy. In order to effectively kill cancerous cells in the limited small temperature range, the accurate temperature control plays an important role on therapeutic efficacy and quality. The past theoretical study on this topic mainly focused on the models for the hysteresis loss-induced heat generation in SPM nanoparticles subject to an alternating magnetic field. Few papers theoretically analyzed the temperature in SPM nanoparticles. Therefore it is essential to theoretically predict the temperature in SPM nanoparticles subject to an alternating magnetic field for hyperthermia of cancer tumor. And the influences of material and magnetism parameters on the temperature in SPM nanoparticles will be also discussed.

0 1 2 3 4 5 6Time (min)

20

40

60

80

Te

mpe

ratu

re (C

)

Experimental Data Measured by Weise

Predicted by This Work250 Oe125 Oe

250 Oe

Figure 1 temperature history in a magnetic nanoparticle subject to external magnetic field

Figure 1 indicates the effects of parameter Hmax on the temperature variation with time. For the external magnetic field 250 Oe, the temperature history predicted by this work agrees well with the measured data [1]. The decrease of the maximum Hmax of applied magnetic field reduces the temperature due to smaller area of hysteresis loop. [1] B. Weise, University of York, Experimental data, 2012.

B-146

PH-09

Study of Change film thickness and bombarded voltage to affect structure and perpendicular exchange bias of

SiO2 / CoO / [Co / Pt] 3multilayer film

C.-C. Chi , C.-H. Hsiao , Chuenhou (Hao) Ouyang , Den-Lo

Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan

e-mail: houyang@mx.nthu.edu.tw

By dual ion beam sputtering system ,we prepare [Co/Pt]3/CoO /SiO2multilayer system and study the PMA(perpendicular magnetic anisotropy) and perpendicular exchange bias with different bombard voltage of RF ion source (VRF = 100,150) and the sputtering time for different thickness of Co (tCo = 0.7, 1.0, 1.3nm[ref], tPt = 2.0nm).

Samples mainly measured by SQUID (superconducting quantum interference device) and HRTEM (high-resolution transmission electron microscopy) that PMA was observed in VRF =150V but not at 100V. With samples prepared at 150V, exchange bias(out of plane) can be measured (HEX Co1.3nm/Pt2nm=-0.4T, HEX Co0.7nm/Pt2nm=-0.75T), which was higher than the sample prepared at 100V(HEX Co1nm/Pt2nm=-0.05T). HRTEM images show the clearly layer structure and direction of Co/Pt with connecting for Co(0001) to Pt(111) of sample at 150V instead of 100V (layer structure distorted seriously in 100V sample). Different layer structures caused by different orientation of CoO in different bombard voltage, lead to different magnetic properties, and the alloy phase of CoPt in the Co/Pt interface was also found which may be hexagonal disorder phase elucidated by multislice result. [1] EPJ Web of Conferences 75, 06003 (2014). [2] JOURNAL OF APPLIED PHYSICS 97, 10J109 (2005)

Figure1: Hysteresis loop from SQUID Figure2: HRTEM image show the layer

structure

B-147

PH-010

Ab Initio Studies of Structure, Electronic and Optical

Properties of Sn-doped Hematite

Taewon Min, Jaekwang Lee*

Department of Physics, Pusan National University, Busan, 46241, Republic of Korea

e-mail: jaekwangl@pusan.ac.kr

-Fe2O3(Hematite) has been spotlighted as one of the very promising solar cell

materials since it is very stable and environment-friendly. Furthermore, iron is the

cheapest and one of the most abundant of all metals in the earth. Even though hematite

is capable of absorbing roughly 40% of the solar spectrum, but its practical use has

been limited due to the low conductivity, weak optical absorption and rapid carrier

recombination. Recently, it has been reported that the substitutional Sn doping

significantly increases and improves the solar cell efficiency of hematite. Here, using

density functional theory, we study the change in electronic and optical properties of

hematite due to the Sn doping, and elucidate the underlying mechanism related to the

efficiency increase. We expect that our study can provide key parameters for

developing novel hematite-based solar

cell device with maximal efficiency

Fig.1 Polaron hopping barrier

calculation. (NEB method)

B-148

PI-01

Magnetic circuit design of an elliptically polarized

undulator

TingYi Chung, FuYuan Lin, ChengHsing Chang, JuiChe Huang, ChengHsiang Chang, JyhChyuan Jan, ChingShiang Hwang

National Synchrotron Radiation Research Center, Hsinchu, Taiwan Chung.albert@nsrrc.org.tw

APPLE II-type elliptically polarized undulator (EPU) has become a workhorse

source in synchrotron radiation facilities, not only for polarized light but also as a

source of soft X-rays. APPLE II consists of four Halbach-type permanent magnet

arrays and can be operated in various modes via a movement of magnet arrays. In order

to minimize the influence of APPLE II on the storage ring, the magnetic circuit must be

optimized to reduce magnetic field integrals for all operation modes. In our design, the

primary objective of center part of the magnet array is to reduce dynamic field integral,

and end terminations need to reduce a gap and phase dependence of static field integral.

Requirements, design processes of the magnetic circuit and preliminary results for

Phase-II EPU at Taiwan Photon Source (TPS) are discussed and explained.

B-149

PI-02

Improvement of stress induced reliability shift in AMR

sensor

Zitu-Tin Lin (a), Wen-Jeng Lin (b) , Fu-Tai Liu (c) , and Yuan-Chieh Tseng (d)

(a)(b)(c) Technology Division Voltafield Technology Corporation, Hsinchu , Taiwan

(d) Materials Science & Engineering (MSE), National Chiao Tung University, Hsinchu, Taiwan.

e-mail: tt.lin@voltafield.com; yctseng21@mail.nctu.edu.tw

When the Moore’s Law goes to the limit, “Industry 4.0” intelligent industry will rise. The development of sensors is the most important application of IOT. Single-chip three-axis Anisotropic Magneto-Resistive (AMR) sensor technology requires the integration of the ASIC (Application-Specific Integrated Circuit) with sensor itself. To have stable yields for production, its biggest challenge will be the reliability verification.

This work proposes a possible solution for the improvement of reliability and stability of the single-chip three-axis AMR sensor. An AMR sensor is constructed by a simple film stack where its 3D trench stack pattern is very sensitive to magnetic response. However, the drawback is that the flexible structure tends to lose the reliability during deformation. In order to circumvent this problem, metal-adjusted sensor and dielectric-adjusted ASIC for stress relief were both employed. We find this approach is able to release the stress and meanwhile improve the AMR sensor‘s reliability.

The proposed method may open opportunities for the AMR sensors to be used in 3C consumer products and even automobile industry. (Figure at left) Stress-induced trench deformation: tensile and compressive comparison of the AMR sensor. For a 3D magnetic sensor, such trenching is used for X/Y/Z sensing. (Figure at right) the order of magnitude of the stress-relief induced by adjusted- dielectric and metal films incorporated into the AMR sensors. [1] Josh Edberg, Global Product Marketing Manager, Honeywell Sensing & Control, The Benefits of AMR Sensor Technology (2015)

B-150

PI-03

Magnetoimpedance characteristics on micromachined

thin-film elements less than 100-micrometers length

H. Kikuchi(a), T. Shima(a), H. Uetake(b), S. Yabukami(b)

(a)Faculty of Enginnering, Iwate University, Morioka, Japan (b) Faculty of Enginnering, Tohoku-Gakuin University, Sendai, Japan

e-mail: hkiku@iwate-u.ac.jp Magnetoimpedance (MI) sensor has higher sensitivity, thus it is expected to be

applied to the medical applications and the nondestructive evaluation, etc. With the demands for the detection of local and micro area, the miniaturization of the sensor element is strongly required. Though a thin-film MI element contributes to the miniaturization of the sensor elements, the demagnetizing effect becomes significant as the problem to be solved [1]. In this study, to reduce the demagnetizing effect, the sensor elements with narrower width, the specific shape and length less than 100 m were fabricated by the micromachining techniques, and the impedance of the elements were evaluated. In the fabrication process, Focus Ion Beam was used for the elements with width less than 5 m. The shapes of sensor elements were rectangular and triangular as shown in Fig. 1. The fabricated elements have from 1 to 20 m wide, from 30 to 100 m long and 1 or 2 m thick, and have an easy axis parallel to the width direction. Fig. 2 shows the impedance changes of the elements against the applied magnetic field. The AC current with 100 MHz and the DC magnetic field were applied to the length direction of the elements. The impedance for the rectangular elements with wider width, 10 or 20 m, have no change, which is attributed to the strong demagnetizing field. We confirmed this point by the electromagnetic analysis. On the other hand, the triangular and several rectangular elements with narrower width, the impedance shows the typical MI profile. Additionally, other several elements, rectangular with 1 m wide and 30 m long or 2 m wide and 100 m long, show the impedance jumps. This jump is caused by the inclined easy axis, which means the easy axis is not kept parallel to the width direction owing to the demagnetizing effect in the width direction. The impedance changes of the elements with 30 m long were demonstrated, which contributes to development of MI sensor with a high spatial resolution. [1] H. Kikuchi, et al., Sensors and Actuators A, 230, 142 (2015).

CoZrNB

w w

l l

Cu electrode

(a) (b) Fig. 1 Shape of MI elements, (a) rectangular, (b) triangular.

0

0.5

1

1.5

2

0 5 10 15 20 25 30 35

w2_l30_rec.w5_l100_rec.w20_l100_rec.w10_l100_rec.w10_l30_tri.w20_l100_tri.

Impe

danc

e ch

ange

Z(

)

Magnetic field H (Oe)

Fig. 2 Impedance change profiles.

B-151

PI-04

Barcode nanowires for multiplexed bioanalysis

S. R. Torati, X. H. Hu, C. G. Kim

Department of Emerging Materials Science, DGIST, Daegu, 42988, Korea.

E-mail: srtorati@dgist.ac.kr

Sequential template electrochemical synthesis of multisegment nanowires with magnetic and non-magnetic segments has been extremely significant for barcoding, multiplexing and biosensing applications [1-3]. Especially, hard magnetic segment with high saturation magnetization and remenance materials are more convenient for multiplexing biological applications. In the present article we have synthesized three different types of magnetic barcode nanowires Co[Ni/Pt/Fe]P/Au by electrochemical deposition technique using a polycarbonate membrane with a diameter of 50 nm and functionalized with DNA for multiplexing analysis. Before synthesis of barcode nanowires, we first synthesized single segment of hard magnetic nanowires. The length of the nanowires was found to be around 6 μm. We compared the magnetic properties of all the synthesized materials and found to be the CoPtP magnetic nanowires have higher saturation and remenence. In order to demonstrate the decoding of barcode nanowires using the magnetoresistance sensor in flow cytometry, we calculated the spatial distribution of the stray magnetic field produced by the barcode nanowire by means of finite element method (FEM) using the commercial Maxwell software. The CoPtP shows higher spatial variation compared to the CoFeP and CoNiP, which means CoPrP is most advantageous composition for the hard magnetic segment. Our main aim for synthesis of this type of nanowires is for the application of multiplex bioanalysis by magnetic method.

References:

[1] K. B. Lee, S. Park, and C. A. Mirkin, 2004, Angew. Chem. Int. Ed., 43, 3048

[2] A. K. Salem, P. C. Searson and K. W. Leong, 2003, Nat.Mat., 2, 668.

[3] S. Anandakumar, V. Sudha Rani, T. S. Ramulu, H. Yang, B. H. Lim, J. Kim, S. S. Yoon and C.G. Kim, 2011, J. Electrochem Soc, 158, E124

B-152

PI-05

The influence of Magnet block imperfections on field

performance for in-vacuum undulators at NSRRC

Chin-Kang Yang, Cheng-Ying Kuo, Yun-Liang Chu, Sei-Da Chen, Jui-Che Huang

National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan

Email: yang.ck@nsrrc.org.tw

In-vacuum undulators are designed to be installed in Taiwan Photon

Source(TPS) and to provide hard x ray energy range between 5 to 20 KeV by using

the 3rd to 9th harmonics of spectrum. Magnetic arrays of these undulators are

designed to minimize the transverse magnetic field roll off and multipoles which can

impact the dynamic aperture, Touschek lifetime, and injection efficiency. However,

magnet block size imperfections and assembly errors will make the transverse

magnetic field roll off and multipoles worse than what they were designed. These

imperfections and errors are inevitable but can be reduced during fabrications.

Calculations and experiments are both done to study the influence. The details of

calculating models, experimental setups, and results are described in this paper.

B-153

PI-06

Magneto-Electronic Hydrogen Gas Sensors

Grace L. Causer(a) (b), Mikhail Kostylev(c), Chris Lueng(c), Frank Klose(a)

(a)Australian Nuclear Science and Technology Organisation, Lucas Heights,

Australia (b)University of Wollongong, Wollongong, Australia

(c)University of Western Australia, Crawley, Australia

In the race to find clean, renewable and abundant energy alternatives to fossil fuels, the spotlight has been shone on hydrogen (H2). However, the high flammability of H2 has so far hindered this revolution globally to a large extent. Robust technologies which address safety and other technical issues related to the storage and usage of H2 fuel need to be developed. Our group recently investigated a novel magneto-electronic device for application in H2 gas leak detection, which overcomes many of the issues associated with previously proposed sensor models[1].

Exploiting the strong affinity of Palladium (Pd) to reversibly absorb and chemically bind H2, resulting in the formation of PdH which expands the Pd lattice constant by up to 3%[2], our prototype device[3] is based on the modification of magnetic, structural and electronic properties that occur upon hydrogenation of a Pd layer in a paramagnetic/ferromagnetic (FM) Pd/Co bilayer nanomaterial. As H2 is absorbed by the Pd lattice, a modification of the perpendicular magnetic anisotropy[4] (PMA) of interfacial Co results, which in turn leads to a variation of the Co layer's ferromagnetic resonance[5] (FMR), a property which is easily detectable by the sensor electronics.

Performing the first in-situ FMR polarised neutron reflectometry (PNR) investigations on the time-of-flight reflectometer PLATYPUS at ANSTO, our group simultaneously probed the hydrogen depth profiles within a Pd layer as a function of external H2 partial pressure (HPP), and correlated them with hydrogen induced changes to the FMR signal in the FM layer. From PNR, a 3.5% HPP resulted in a 0.93 nm increase in the Pd layer thickness of a Pd(12nm)/FM(10nm) bilayer, and we found the density of H atoms to the density of Pd atoms to be in a ratio of 0.42/1. In this state a 30 Oe field shift of the characteristic FMR absorption peak taken at the frequency of 4.3GHz was observed, analogues to a variation in the contribution of the PMA to the FMR frequency. Trialling the hypothesis that H2 absorption occurs more readily in bilayers with reduced Pd dimensionality, investigations into the impact of Pd layer thickness on the devices time response to H2 exposure were also conducted. The success of a hydrogen sensor relies on its ability to effectively and rapidly detect the presence of H2. Exposing a Pd(10nm)/Co(5nm) film to a highly dilute 0.06% HPP resulted in a large decay constant of 680 seconds, a time response which has since been found to be reduced by three orders of magnitude through nanopatterning the film. [1] T. Hubert et al., Sen. Actuat. B, 157 329 (2011) [2] W.J. Buttner et al., Int. J. Hydrogen Energ. 36 2462 (2011) [3] C.S. Chang, M. Kostylev et at., Appl. Phys. Lett. 102 142405 (2013) [4] B.N. Engel et al., Phys. Rev. Lett. 67 1910 (1991) [5] A.G. Gurevich et al., Magnetisation Oscillation and Waves, N.Y.: CRC Press (1996)

B-154

PI-07

Application of Tunnel Magnetoresistance Sensor in two-dimensional magnetic tracking

Xuan-Thang Trinh(a), Jen-Tzong Jeng*,(a), Van-Su Luong(a), Chih-Cheng Lu(b)

(a) Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

(b) Institute of Mechatronics Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

e-mail: jtjeng@kuas.edu.tw

In this experiment, a two-dimensional (2D) position detection device using a tunnel-magnetoresistance (TMR) sensor combined with orthogonal gradient coils was designed and fabricated. Typical magnetic trackers rely on three-axis field sensing to detect the AC or pulse DC fields induced by dipole transmitters [1]. In our design, a single axis TMR sensor is the target object which converts the position information into the output voltage with an in-phase and quadrature synchronous detector, as show in Fig. 1(a). The sensing direction of the TMR sensor was set perpendicular to the plane of two gradient coils. The two coils were driven by sine wave currents at 1 kHz with 90o phase difference to generate the fields with uniform gradients along the x- and y- axes of the plane, as shown in Fig. 1(b) and (c). The distances from the sensor to the two coils were analysed numerically to achieve the maximum linear range, which corresponds to the detection area of the device. The observed result shows that the device with gradient coils and a TMR sensor is promising in applications related to 2D magnetic field mapping to allow the sensor position be determined accurately in real-time during scanning.

[1] Eugene Paperno, Ichiro Sasada, and Eduard Leonovich, "A New Method for Magnetic Position and Orientation Tracking", IEEE Transactions on Magnetics, 37(4), 1938-1940 (2001).

(a) (b) (c) Fig. 1 The 2D tracker: (a) schematic diagram, and field distributions of (b) x-coil and (c) y-coil.

B-155

PI-08

Synthesization of magnetic particle for adsorption of bovine serum albumin in microfluidic

Yu-Chi Kuo, Yin-Chou Huang, Chao-Ming Su, Shyh-Liang Lou, Tzong-Rong Ger

Department of Biomedical Engineering, Chung Yuan Christian University, Taoyuan,

Taiwan e-mail: sunbow@cycu.org.tw

Magnetic separation is a recent developing technology and mostly applied in the field of bioseparation and protein purification. Compared to conventional separation which needs a lot of steps and samples to get a protein isolate, the advantages of magnetic separation are attributed to its speed, accuracy and simplicity. Our goal is to combine microfluidic channel with magnetic nanoparticles, which could effectively catch proteins and save samples as shown in Fig. 1. Magnetic nanoparticles (Fe3O4) were prepared by chemical precipitation. The microfluidic device was fabricated by PDMS. The size of magnetic particles is about 27± 0.067 nm. The channel diameter is 850 m.　 The magnetic particles components were measured by FTIR where, the characteristic band of Fe3O4 at 570 cm-1 is shown in Fig. 1(a). The current experimental results showed that the adsorption of BSA on magnetic nanoparticles (Fe3O4) was affected by concentration and pH. The best Fe3O4 concentration was 4mg in 1ml BSA solution. BSA solution was 1mg solid BSA in 1ml Milli-Q water. Effect of pH on adsorption was evaluated in the range of pH 3.5-5.5 shown in Fig. 1(b). The best adsorption pH was at pH 3.5. The adsorption of BSA on magnetic particles reached to 45% while the microfluidic device attained 40% adsorption. The result showed that combining microfluidic channel and magnetic nanoparticles can be achieved and effective in catching proteins and saving samples.

Fig. 1. Schematic of magnetic nanoparticles for BSA adsorption with applied external AC field in micro-channel. (a) Magnetic nanoparticles (Fe3O4) FTIR result. (b) The adsorption of BSA on magnetic nanoparticles (Fe3O4) percentage in different pH.

(a) (b)

B-156

PI-09

Principle of magnetic circuit design for a Particle Accelerator Undulator

Jui-Che Huang, Chin-Kang Yang, Ching-Shiang Hwang

National Synchrotron Radiation Research Centre ,HsinChu Taiwan e-mail: huang.juiche@nsrrc.org.tw

High brilliant light from a third-generation light source is the key motive and drive to develop an advanced insertion device. Of two typical approaches for generating high brilliance photons, one is to improve the quality of the electron beam. Constructing a electron storage ring of low emittance, such as at TPS, NSLSII, and MAX IV, becomes important to pursue a diffraction-limited light source. Another approach is to improve the quality of the photon beam of the light source. To ensure a highly brilliant light source and stable operation of the storage ring demands a stringent field quality of undulators. Magnetic circuit design is particular important and become state of art on undulator construction. Design criterion include properties of magnet material, period length , magnetic peak field , K-parameter, static and dynamic field integrals , termination end pole design and so on. This paper describes principles of undulator magnetic circuit design and some examples of Taiwan Photon Source undulator are presented.

B-157

PI-10

Optimizing the magnetic properties of cascaded spin

valve ellipses for magnetic field sensors

Y. C. Su(a), K. W. Lee(a), Y. C. Lee(a), V. S. Luong(c), J. H. Hsu(b), J. T. Jeng(b), C. R. Chang(b) , Jen-Tzong Jeng(c) and Jong-Ching Wu(a)

(a)Department of Physics, National Changhua University of Education, Taiwan (b)Department of Physics, National Taiwan University, Taiwan

(c)Department of Mechanical Engineering, National Kaohsiung University of Applied

Sciences e-mail: phjcwu@cc.ncue.edu.tw

The spin valve (SV) based field sensor has better signal output than anisotropy

magnetoresistance (AMR) sensor. A SV multilayer with an in-plane magnetization

anisotropy consisting of Ta 2/ IrMn 10/ CoFe 2.5 / Cu 2/ CoFe 2 / NiFe 2.5/ Ta 5

(thickness in nanometers) is prepared by means of sputtering. A field cooling at 550 K

under an external magnetic field of 2 KOe is then employed. Nano-patterning is carried

out by using a standard electron beam lithography in conjunction with ion-milling

etching technique. A standard four-terminal ac lock-in measurement is employed to

characterize the reversal behaviors. We find the reversal behaviors of cascaded SV

device can be controlled by gap value and field cool again.

Figure 1. (a) Schematic and (b) a representative of SEM micrograph of the SV device.

Figure 2. Gap dependence of (a) MR ratio, (b) center shift, and (c) of a cascaded SV

device after field cool again. [1] G. Riger, K. Ludwig, J. Hauch, W. Clemens, Sensors and Actuator A,vol91,May (2001).

B-158

PI-11

Special magnetic structure for cell sorting by novel 3D

printing

Ming Da Yanga,b*, Yu Ting Huanga, Mean Jue Tunga a Industrial Technology Research Institute, Hisinchu, Taiwan, R.O.C

b National Tsing Hua University, Hisinchu, Taiwan, R.O.C

*E-Mail : itri960331@itri.org.tw One of the current challenging developments in biomedical science is transplantation therapy and

regenerative medicine. To separate the useful stem cells is key issue. Magnetic - activated cell sorting

is a method for separation of various cell populations depending on their surface antigens (CD

molecules) invented by Miltenyi Biotec, which uses superparamagnetic nanoparticles and columns..

In this research we focus on the design of a magnetic sorting device for cell separation and

purification. Main tasks include the high gradient magnetic fluid channel, magnetic field design and

the automatic cell sorting procedure. The magnetic column can be designed by novel 3D magnetic

printing. The spiral magnetic structure can be printed by combining sintered magnetic powder with

biodegradation and biocompatibility of PLA. The simulation of magnetic gradient for period spiral

magnetic wire (diameter : 0.5mm) attend to 3800T/m. From the overnight incubation of KG1a

(non-adherence) cells cultures, desired cells are targeted with antibody complexes recognizing the

superparamagnetic nanoparticles and their surface antigens (CD34). With a multi-channel magnetic

chamber, the high magnetic gradient can be extended to the interior of the chamber, and therefore the

sorting efficiency can be increased. The experimental results show 90% sorting efficiency. An

automatic cell separation device has been developed and verified.

B-159

3rd August, Wednesday

B-160

DA-01

Improved Liquid-Phase Detection of Biological Targets Based on Brownian Relaxation of Magnetic Markers

K. Enpuku

Department of Electrical Engineering, Kyushu University, Fukuoka, Japan. e-mail: enpuku@sc.kyushu-u.ac.jp

We have been developing a liquid-phase detection technique of biological targets utilizing Brownian relaxation of magnetic markers and highly sensitive magnetic sensors. In this method, the bound and unbound (free) markers can be magnetically distinguished, eliminating the time-consuming washing process for marker separation. Although a signal from the free markers is zero in an ideal case due to their short Brownian relaxation time, it exists in a real sample on account of the aggregation and precipitation of free markers. This signal is called a blank signal, and it degrades the sensitivity of target detection. To solve this problem, we propose improved detection methods. First, we show methods for sample preparation and magnetization of bound markers. We introduce a reaction field during the binding reaction between markers and targets. We additionally introduce a dispersion process after magnetization of the bound markers. Using these methods, we can obtain a strong signal from the bound markers without increasing the blank signal of the free markers. Next, we present a field-reversal measurement procedure, with which the signal from the markers in suspension can be differentiated from that of the precipitated markers. Using this procedure, therefore, we can eliminate the signal from the precipitated markers.

We detected biotin molecules by using these methods. In an experiment, we used biotin molecules as targets. The biotins were immobilized on the surfaces of large polymer beads with diameters of 3.3 m. They were detected with 　streptavidin-conjugated magnetic markers (FG beads, Tamagawa Seiki). For detection, 60 µL of the sample including bound and free markers was used. Figure 1 shows the relationship between the number of biotin molecules, NB, and the detected signal, Bs, which was measured with SQUID and MR sensors. As shown, good correlation was obtained between NB and Bs, confirming that the liquid-phase detection was performed correctly. The minimum detectable molecular number concentration was 1.8 × 10-19 and 7.2 × 10-18 mol/ml when the signal is detected with the SQUID and MR sensor, respectively, indicating high sensitivity of the present method.

100

101

102

103

100 101 102

SQUIDMR

Bs (

pT)

NB (104/60 L)

Fig. 1. Detection of biotin molecules.

B-161

DA-02

Magnetization reversal of self-assembled one-dimensional chains of Fe3O4 nanoparticles

Alexander Samardak1, Alexander Davydenko1, Alexey Ognev1,

Yoo Sang Jeon2, Young Soo Choi2, Young Keun Kim2 1School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russia

2Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of

Korea

samardak.as@dvfu.ru

Magnetic nanoparticles (NPs) generate growing interest of scientists not only

from physics and chemistry areas, but also from biomedicine including cancer research.

By means of self-organization, NPs can form agglomerates, superlattices or ordered

arrays consisting of finite number of nanoparticles. The understanding of magnetic

behavior of coupled NPs in chains will open up new routes of their practical usage.

Magnetite has the unique magnetic and transport properties due to the existence

of Fe cations in two valence states (Fe2+ and Fe3+) in the inverse spinel structure. For

practical application, especially in hyperthermia and drug delivery, magnetite

nanoparticles with the diameter from 20 up to 200 nm are more essential, thanks to

their ferromagnetic properties at normal conditions. The most interest is provoked not

by single nanoparticles, but also their magnetostatically coupled arrays self-organized

under an external excitation.

Here we present results of experiments and micromagnetic simulations of

magnetization reversal in single magnetite (Fe3O4) NPs and their one-dimensional

chains. In this study, we have chosen to employ ferromagnetic Fe3O4 multi-granule

nanoclustered NPs [1], because we need large (e.g., 100 nm and higher) and uniform

sized NPs to form ordered nanochains. Our systematic study by magnetic force

microscopy, first order reversal curves (FORC) analysis, micromagnetic simulations

and analytical calculations reveal that magnetite nanoparticles with 200 nm diameter

have three dimensional vortex configuration at demagnetized state leading completely

different magnetization reversal in single NPs and their nanochains compare to 100 nm

single domain NPs.

This work was supported by the Russian Ministry of Education and Science (Contract

14.575.21.0039 (RFMEFI57514X0039)) and RFBR (16-02-01015 A).

References 1. Lee J.S., Cha J.M., Yoon H.Y., Lee J.-K., Kim Y.K., Magnetic multi-granule nanoclusters:

A model system that exhibits universal size effect of magnetic coercivity // Scientific Reports, 5, art. no. 12135, (2015).

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Rotational hysteresis loss analysis for randomly oriented α”-Fe16N2 nanoparticles assembly

Masahiro Tobise, Tomoyuki Ogawa and Shin Saito

Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6–6–05 Aoba, Aramaki, Aoba–ku, Sendai 980–8579, Japan

e-mail: masahiro_tobise@ecei.tohoku. ac.jp

The metastable ”-Fe16N2 with b.c.t structure has been paid much attention as a new candidate for isotropic hard magnetic material exhibits high Ms of 234 emu/g and relativerly high Ku of ≃107 erg/cm3 [1].

As a hard magnetic material, the issues of this ”-Fe16N2 nanoparticles assembly are increse in intrinsic magnetocrystalline anisotopy of ”-Fe16N2 itself and decrese in intergranular exchange and magnetostatic couplings among ”-Fe16N2 nanoparticles. Therefore it is very significant to evaluate anisotopy field of particles (Hk

ptc) to improve coercivity. Almost single-phase ”-Fe16N2 nanoparticles starting from ɤ-Fe2O3 and Fe3O4 are

prepared through optimaizing temperature and duration time of reduction and nitriding. We discuss the degree of magnetic interactions based on the experimental results obtained by the rotational hysteresis loss (Wr) analysis using randomly oriented nanoparticles. Switching field (Hp) also determined by this methods with the magnetic field up to 15 kOe. Magnetization Ms and coercivity Hc were measured by VSM with the maximum applied magnetic field 14.5 kOe at the temperature 300 K.

The values of Ms, Hc, Hp and Hkptc are listed in the tabale 1 and the values of Hc/Hk

ptc and Hp/Hk

ptcare plotted in Fig.1. The values of Hc/Hkptc and Hp/Hk

ptc are 0.17 and 0.33 for ”-Fe16N2 nanoparticles produced from ɤ-Fe2O3 and 0.10 and 0.28 for ”-Fe16N2 nanoparticles produced from Fe3O4, respectively. These indicate that strong magnetic interactions still remain. More detail on the relationship between these magnetic properties and microstructure observed by TEM is discussed.

[1] T.Ogawa, Y.Ogata, R.Gallage, N.Kobayashi, Naoaki Hayashi, Y.Kusano, S.Yamamoto, K.Kohara, M.Doi, M.Takano and M.Takahashi, Appl. Phys. Express,6 (2013) 073007

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0 20 40 60 80 100 120 140 160 1800

10

20

30

40

50

60

70

(c)

T

( oC

)

Time(s)

18 KA/m

22 KA/m 26 KA/m 30 KA/m 34 KA/m

5mg/mL

Core-Shell Magnetic Nanostructures with high Hyperthermia Capability

Shuli He(a,b), Hongwang Zhang(b), Xueyan Li(a), Yihao Liu(a) , Chen Liu(a) , Hao Zeng(a*)

(a) Department of Physics, Capital Normal University, Beijing 100048, P. R. China

(b) Department of Physics, University at Buffalo-SUNY, Buffalo, New York 14260, United States

e-mail: haozeng@buffalo. edu Magnetic hyperthermia treatment has gained extensive attention recently because

of their deep tissue penetration, ease of control and actuation on-demand. Recently, magnetic nanoparticles (NP) have been strongly suggested for hyperthermia cancer treatment in radio-frequency (RF) magnetic fields. In order to minimize the potential side effects arising in this therapy, the dosage of NPs should be as low as possible while achieving sufficient heating. Therefore, it is desirable to develop novel NPs with high specific loss of power (SLP).[1] In the superparamagnetic regime where Neel relaxation is dominant, the key to realizing high SLP is a high saturation magnetization and a moderate anisotropy. [2,3] In this paper, MnFe2O4@Mn0.5Co0.5Fe2O4 core-shell nanoparticles with tunable core and shell dimensions were synthesized. The high saturation magnetization was mainly contributed by MnFe2O4 core, and the anisotropy can be tuned by the thickness of hard magnetic shell. 18 nm MnFe2O4@ 2nm Mn0.5Co0.5Fe2O4 core-shell nanoparticles exhibit a large SLP value as high as 3600 w/g in an RF field with a frequency of 390 kHz and amplitude of 34 kA/m.

Keywords: hyperthermia, core-shell magnetic nanostructures, magnetic anisotropy

REFERENCES: [1] R.Hergt, S. Dutz, J. Magn. Magn. Mater., 311, 187 (2007). [2] J. Lee, J. Jang, J. Choi, S. Moon, S. Noh, J. Kim, J. Kim, I. Kim, K. Park, J. Cheon, Nature Nanotechnol., 6, 418 (2011). [3] H. Zhang, H. Huang, S. He, H. Zeng, A. Pralle, Nanoscale, 6, 13463 (2014).

(a) Fig. 1 TEM image of (a) 18 nm MnFe2O4 NPs, (b) 18 nm MnFe2O4@ 2nm

Mn0.5Co0.5Fe2O4 core-shell nanostructure, (c) Heating curve of sample b This work was supported by National Science Foundation of China (51571146).

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Finite size effect on magnetic transitions of

La1-xSrxMnO3 nano-particles with x=0.1~0.4.

Y. S. Chen, K. L. Liang and J. G. Lin *

Center for Condensed Matter Sciences, National Taiwan University, Taiwan (R.O.C)

*e-mail: jglin@ntu.edu.tw

Mixed-valence magnites exhibit double exchange interaction between Mn3+ and Mn4+ which induces simultaneously metallic and ferromagnetic (FM) transitions, resulting in colossal magnetoresistance (CMR) effect. Among these half-doped magnites, Sr doped LaMnO3 (La1-xSrxMnO3, LSMO) attracts intensive attention for the room-temperature ferromagnetism and high conductivity at x=0.2~0.4. The applications for CMR devices and the electrodes of fuel/solar cells have been proposed. Due to the strong interaction between magnetic and conductivity incorporating with structure transitions, LSMO shows a rich phase diagram with the distortion of crystal structure reported in nano-grained LSMO [1] for x=0.125. Recently the ferromagnetic transition and CMR of LSMO nanoparticles with x=0.1 was reported to occur at room-temperature which is much higher than the TC of bulk sample (~150K). The distinct difference between nano-particle and bulk raises an issue of doping induced structural effect on the magnetism of nano-sized LSMO. However, the x dependent study on nano-particle is very rare. In this work, LSMO nano-particles with x=0.1 to 0.4 are prepared with sol-gel method. High energy X-ray diffraction (XRD) is applied to identify the structures of LSMO nano-particles. The particle size of around 16~19 nm and the nominal composition are confirmed with scanning electron microscope and inductively coupled plasma atomic emission spectroscopy. XRD results indicate a rhombohedral symmetry for all samples different from that of bulk materials which are well-known having an orthorhombic to rhombohedral transition from x=0.1 to 0.2. Temperature and field-dependent magnetization are measured. The doping dependence of magnetic properties in nanoparticles is also different from the results of bulk sample. Combining the structural and magnetic results, it prevails that the magnetic transition temperature is dominated by the lattice parameters instead of Sr-doping. This result is attributed to the size confinement on the percolation probability. Thus, the variation of lattice constant dominates the Mn-Mn exchange coupling in nano-sized LSMO. + This work is financial supported by Minister of Science and Technology of R. O. C. with the project no. NSC102-2112-M-002-MY3 [1] Anulekha Dutta and et al., Phys. Rev. B 68, 054432 (2003)

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Preparation of Fe Nanoparticles by Submerged Arc Discharge Method

Kuo-Hsiung Tseng (a), Mei-Jiun Chen(a), Chaur-Yang Chang(a), Meng-Yun Chung(a)

(a) Department of Electrical Engineering, National Taipei University of Technology,

Taipei 10608, Taiwan, R.O.C. e-mail: khtseng@ee.ntut.edu.tw

Magnetic nanoparticle fluid has multiple purpose which can be applied on military, aviation and optics. Especially in medical field, magnetic nanoparticle fluid can be used on cancer detection or tumor removal. Fabricating nanoFe by electrical discharge machining with no chemical elements is a brand new method known as Submerged Arc Discharge Method (SADM). By using ultraviolet-visble (UV-Vis) spectroscopy, Zetaseizer, Scanning Electron Microscope (SEM) and Vibrating Sample Magnetometer (VSM), we can get the nano characters and magnetic properties of the nanoFe. The experimental results of the surface plasmon resonance (around 260nm) and zeta potential (around -15mV) are obtained. They showed that the nanoFe fabricated by the EDM was considered as nano size and had good suspension stability. By comparing the magnetic properties of the nanoFe fabricated by SADM and other existed chemical method, the former method which is easily prepared, lower cost and no chemical ingredient is another way for preparation the green and human-harmless nanoFe.

Keywords: Fe Nanoparticles, Magnetic nanoparticle fluid, Submerged arc discharge method, Vibrating sample magnetometer

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ab initio calculations to study interfacial intermixing of core(-Fe2O3)/shell(CoO) nanoparticles and superexchange effect at interface

C.-C. Chi (a), C.-H. Hsiao (a), E. Skoropata (b), J. van Lierop (b) , Chuenhou (Hao) Ouyang (a)

(a) Materials Science and Engineering, National Tsing Hua University, Hsinchu,

Taiwan (b) Department of Physics and Astronomy, University of Manitoba, Winnipeg,

Manitoba R3T 2N2, Canada e-mail: houyang@mx.nthu.edu.tw

Previousxstudies[1]xshowedxbetterxmagneticxpropertiesxofxcore(-Fe2O3)/shell(CoO) nanoparticles then the single phase nanoparticles. The main reason causing the promotion of magnetic properties was surmised by intermixing of core/shell interface.

We found that the intermixing in core/shell interface was caused by Co into octahedral vacancies of -Fe2O3[2] by HRTEM(High-resolution transmission electron microscopy) images, EDS (Energy-dispersive X-ray spectroscopy)and first principle simulated calculation with VASP (Vienna Ab-initio Simulation Package).But simulated calculation and previous studies[1] also showed the lower magnetization of sample with deeper Co diffusion. EELS(Electron Energy Loss Spectrum) of interface showed the existence of oxygen between iron and cobalt, therefore we suspected the magnetization affected by the superexchange effect we suspected ,which related to the metal-oxygen-metal bounding length and bounding angle. Therefore we build the simulated structure based on HRTEM images and calculated the magnetization by VASP to realize the superexchange effect of Co, O and Fe at interface. [1] Physical Review B, 89, 024410 (2014). [2] J. Appl. Phys. 117, 17E135 (2015)

Figure1: EELS of interface Figure2: HRTEM image and simulated connecting

structure By HRTEM(High-resolution transmission electron microscopy) images, EDS (Energy-dispersive X-ray spectroscopy)and first principle simulated calculation with VASP (Vienna Ab-initio Simulation Package)we found

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Spin transport in magnetic heterostructures

based on topological insulators

J. Kwo(a), Y. T. Fanchiang(b), C. N. Wu(a), H. Y. Lin(a), K. H. Chen(a), J. G. Lin(c),

M. Hong(b), and S. F. Lee(d) (a) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

(b) Graduate Institute of Applied Physics and Department of Physics, National Taiwan

University, Taipei 10617, Taiwan (c)Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617,

Taiwan (d)Institute of Physics, Academia Sinica, Taipei 115, Taiwan

Topological insulators (TIs) are promising materials for spintronics due to their helical

Dirac fermions, which were electrically tunable to realize devices operated in a wide

range of spin transport regime. To demonstrate the pronounced field effect on TIs, high

quality 3-D TIs thin films of Bi2Se3 and Bi2Te2Se had been obtained by van der Waals

epitaxy on atomic-layer-deposited high-κ dielectric such as Al2O3 and Y2O3/Al2O3

multilayers using molecular beam epitaxy. Sharp topological surface states (TSS) were

observed by ARPES, plus the weak antilocalization effect. We also demonstrated the

large gating effect using a back gate. The study on spin transport of TSS has been

conducted by spin pumping. Very strong spin-charge conversion was observed in TI/FM

bilayers, with a charge current density Jc about 3-5 times higher than conventional

NM/FM bi-layers. Spin pumping in TI films on ferromagnetic insulator YIG has detected

unusual negative resonance field shifts (Hres) with respect to bare YIG film. Possible

causes are addressed, along with the results of current induced spin torque ferromagnetic

resonance in the YIG-based bilayer structures toward dissipationless spintronic

applications.

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Transport of spin waves and the interaction with domain walls in magnetic nanowires with perpendicular

anisotropy

Liang-Juan Chang(a), Jun-Zhi Liang(b), Shang-Fan Lee(a)* (a) Institute of Physics, Academia Sinica, Taipei 115, Taiwan

(b) Department of Physics, Fu Jen Catholic University, Taipei 24205, Taiwan Email: leesf@sinica.edu.tw

Manipulation of the dynamics of spin wave (SW) and the SW-induced domain wall motion in

magnetic nanostripes with perpendicular anisotropy is studied theoretically and by simulation.

Moving a DW in a controlled manner is an important issue for various applications. Utilizing

spin-polarized electric current via angular momentum transfer and magnetic fields via energy

dissipation are well known ways of control for DW motion. Spin waves can drive the DW effectively

due to the magnonic spin current. It has been theoretically shown that magnonic spin torque causes a

DW to propagate in the direction opposite to the SWs and that linear momentum transfer causes a DW

to propagate in the direction of SWs. The transmission fractions of SW in the presence of DW are

determined by spin orientation of the DW. When a SW approaches a DW, fluctuation of

magnetization appears in the DW region, which gives rise to an effective anisotropy field acting on

the DW. The effective anisotropy field exerts a torque to rotate the DW magnetization. The directions

of the SW induced DW motion and the transmission coefficient for the propagating SW across the

DW are dependent on the in-plane tilt angle of the wall magnetization. The spatial variation of the

normalized My component without the DW and with a DW having tilt angle φ are simulated and

analyzed in details. The dependence of transmission ratios T on the tilt angle of the DW are shown in

Figure 1. Results on various SW amplitude and frequency will be presented.

Figure 1. (a) The spatial variation of the normalized My component without the DW. (b)-(d) The snapshot of the SW amplitude in the nanostripe including a DW with selected values of tilt angles, 50, 130, and 170 deg. (e) The transmission ratios T as a function of the tilt angle of the DW

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Spintronics with small molecules

M. Galbiati, S. Tatay, S. Delprat, C. Barraud, P. Seneor, R. Mattana and F. Petroff

Unité Mixte de Physique CNRS/Thales, Palaiseau, France

e-mail: richard.mattana@cnrs-thales.fr

Organic/molecular spintronics is a rising research field at the frontier between

spintronics and chemistry. Beyond, plasticity and low cost, organic materials were first

seen as very promising for spintronics devices due to their expected long spin lifetime.

While originally overlooked it was later unveiled that opportunities arising from

chemistry could also lead to develop new spintronics functionalities. Among them, we

have shown the opportunity to tailor spintronics thanks to hybridization between

ferromagnetic leads and discrete molecular orbitals [1]. While initially developed for

Alq3 this could be applied to any molecule. We will present spin dependent transport

experiments on organic materials such as small molecules (Alq3, CoPc [2]) and

self-assembled monolayers (alkyl-phosphonic acids) [3,4].

[1] Clément Barraud et al., Nature Physics 6, 615 (2010) [2] Clément Barraud et al., Phys. Rev. Lett. 114, 206603 (2015) [3] Marta Galbiati et al.. Adv. Mater. 24, 6429 (2012) [4] Sergio Tatay, et al., ACS Nano 6, 8753 (2012)

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Voltage-controlled magnetization switching in spintronic devices

Wei-Gang Wang

Department of Physics, University of Arizona, Tucson, Arizona 85721, USA

E-mail: wgwang@physics.arizona.edu

Controlling the magnetic properties of solids by electric fields has been an interesting research

subject, not only because of the intriguing correlation between the electric and magnetic orders in

solid-state systems, but also the potential applications in ultra-low energy spintronic devices. In the

past, research has mostly been carried out with multiferroic materials and magnetic semiconductors.

Recently, more effort was focused on 3d transition ferromagnetic metals. Especially in heavy

metal/ferromagnet/oxide (HM/FM/oxide) structures where the magnetic anisotropy has an interfacial

origin, electric fields can cause a marked change on the magnetic anisotropy energy. This

voltage-controlled anisotropy (VCA) can be understood by the electric field induced charge transfer

among different d orbitals of the FM. The order of this effect is around 100 fJ/Vm and it vanishes with

the removing of the electric fields.

Another approach is to alter the magnetism by electrically controlling the oxidation state of the 3d

FM at the FM/oxide interface. It has been demonstrated that the thin FM film sandwiched between a

heavy metal layer and a gate oxide can be reversibly changed from an optimally-oxidized state with a

strong perpendicular magnetic anisotropy to a metallic state with an in-plane magnetic anisotropy, or

to a fully-oxidized state with nearly zero magnetization, depending on the polarity and time duration

of the applied electric fields. This is a voltage controlled magnetism (VCM) effect, where both the

saturation magnetization and anisotropy field of the 3d FM layer can be simultaneously controlled by

voltage in a non-volatile fashion[1]. Although the speed of this effect is slow, the magnitude of

magnetic anisotropy change can reach > 10 pJ/Vm, much larger than that of previous VCMA effects.

A very different time dependence on voltages with different polarities was observed, reflecting the

asymmetric energy barrier at the FM/oxide interface.

In this talk, I will discuss both VCA and VCM effects in perpendicular magnetic tunneling

junctions (pMTJs), gated Hall bars and other devices structures. In particular, focus will be given on

enhancing the voltage effects in pMTJs with large tunneling magnetoresistance and large anisotropy

energy density [2]. This work was supported in part by C-SPIN, one of six centers of STARnet, a

Semiconductor Research Corporation program, sponsored by MARCO and DARPA, and by NSF

(ECCS-1310338).

[1]C. Bi, Y. Liu, T. Newhouse-Illige, M. Xu, M. Rosales, J. W. Freeland, O. Mryasov, S. Zhang, S. G. E. te

Velthuis, and W. G. Wang, Phys. Rev. Lett. 113, 267202 (2014).

[2] H. Almais, T. Newhouse-Illige, M. Xu, Y.H. Xu, C. Bi and W.G. Wang, submitted.

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Thermal spin detection of inverse spin Hall effect by longitudinal spin Seebeck effect

Ssu-Yen Huang

Department of Physics, National Taiwan University, Taipei, Taiwan

The exploration of spintronics has evolved from manipulation of spin-polarized

currents to that of pure spin currents to increase energy efficiency. The generation and

the detection of pure spin currents have been intensively studied to search for materials

with large spin Hall angle SH, which determines the efficiency of charge and spin

current conversion. The methods to determine SH usually accompany the difficulty by

involving complicated interfaces in device structures and some parasitic effects such as

current shunting, planar Hall effect, anisotropic magnetoresistance, etc. In this work,

we report self-consistent and versatile measurements in metal/ferromagnetic insulator

heterostructures to determine the spin Hall angle and spin diffusion length of selected

5d metals, ferromagnet, and even antiferromagnet. The spin current is injected by

utilizing longitudinal spin Seebeck effect in the magnetic insulator yttrium iron garnet

(YIG). The simple metal/insulator bilayer structure, which lacks the charge carrier in

the FM insulator, can prevent the results from being affected by most of the parasitic

effects in FM metals. By varying the thickness of the spin current detection layer

comparable to the spin diffusion length, we determine the spin Hall angle SH and the

spin diffusion length SF of important metals simultaneously. In the case of magnetic

materials, surprisingly, we observe the pronounced inverse spin Hall signal exist in

ferromagnet and antiferromagnet, which is independent of its magnetic ordering. The

sign of SH for Ta, W, and Cr is opposite to that of Pt, Au, and Py. Their spin diffusion

lengths, revealed by thickness dependent measurements, are in good agreement with

previous literature. Our study also highlights the importance of the resistivity of the

thin film in the determination of SH is the key parameter in acquiring large ISHE

voltage.

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Magnetic wire memory is attractive for future ultra-low power consumption data storage. To

prepare the magnetic wire, most of the research group are using a dry etching or lift-off method. However, the process makes several damages to the sample. Therefore, we have proposed a new fabrication technique of the magnetic wire without the etching process. It can be realize by using nano-imprint method on a plastic substrate. The wire edge is very smooth compared with that of the magnetic wire made by lift-off method. Therefore, the critical current density for domain wall motion of the nano-imprinted magnetic wire can be reduced down to one-tenth compared with that made by lift-off method. And also, using this method, very narrow TbFeCo magnetic wire of 45nm in width can be fabricated and uniform magnetic domain patterns are recorded on it.

I. INTRODUCTION Typical semiconductor memory, such as DRAM and SRAM are volatile memory. Therefore, they

require a large amount of standby power to hold the data. To improve the power problem, non-volatile MRAM research and development have been actively carried out. In the MRAM studies, a domain wall motion type MRAM has been proposed and the practical demonstrations have been reported. On the other hand, another type of domain wall motion memory named as racetrack memory has been proposed and demonstrated. The memory area is long enough, a lot of data can be stored. As the typical racetrack memory material, FeNi and Co/Ni multilayer have been used. However, to use as a data storage, their domain wall coercive force (Hw) of these materials are very small and the critical current density (Jc) for the domain wall motion are large. Therefore, we have reported performance of amorphous TbFeCo magnetic wire. The Hw of TbFeCo is much larger than those of them, and also the Jc is less than those of them [1-3]. In order to reduce the Jc, the magnetic wire fabrication process should be reconsidered. In figure 1 (a), a conventional magnetic wire fabrication method is made by this dry process, such as an etching or lift-off. Most magnetic wire is prepared by this method. It is difficult to make uniform wire. As a one example, SEM image of magnetic wire edge made by the conventional method is shown at the bottom of Fig.1 (a). On the other hand, our proposal of new process [4] is shown in the figure 1 (b). Once the mold with fine wire pattern is prepared, just same wire patterns can be fabricated on the plastic substrate by using nano-imprint technology. The SEM image of the nano-imprinted magnetic wire is shown at the bottom of the figure 1 (b). Thus, the wire edge becomes very smooth. In this report, the

Magnetic recording on the RE-TM /Pt magnetic wire deposited on nano-imprinted plastic substrate

Hiroyuki Awano*, Satoshi Sumi, Yuichiro Kurokawa, Do Bang, Akihiko Moribayashi,

Ryogo Yoshimura, and Tsukasa Asari Toyota Technological Institute, Nagoya, Aichi 468-8511, JAPAN

e-mail : awano@toyota-ti.ac.jp

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nano-imprinted magnetic wire and the recording results are reported. II. EXPERIMENTAL PROCEDURES AND RESULTS

The 45nm width, 100nm depth, and 20 m-length TbFeCo magnetic wires were fabricated using our proposed nano-imprint technique in Fig.1 (b). The SEM image is shown in the figure 2(a). This method is similar to the optical disk fabrication and the substrate cost is very low compared with that of the Si substrate. When a magnetic film is deposited onto the grooved PC substrate, magnetic nanowire can be prepared with smooth wire edge. The 10-nm-thick Tb26Fe66.8Co7.2 film was directly grown on the nano-imprinted plastic substrate by RF magnetron sputtering. A 2nm Pt layer was subsequently capped on the film. The ultimate vacuum was less than 2 x 10-8Torr and Ar sputtering gas pressure of 1 mTorr was kept during grown films.

Using a very small magnetic head with 50nm x 50nm magnetic core, magnetic recording was performed on the sample. The recorded pattern is observed by TMR head scanning microscope technique [5]. The signal shows magnetic field form the recorded domains. The TMR head sensor size is 30nm. The spacing between the sample and TMR head is about 2nm. The observed result is shown in the figure 2 (b). As you can see in the figure, uniform magnetic recorded domains are confirmed. Thus, by using new magnetic wire fabrication method, narrow magnetic wires can be fabricated. Moreover, by using magnetic head and TMR sensors, fine magnetic recording and the observation can be performed.

III. CONCLUSION New magnetic wire fabrication method using nano-imprint technique with plastic substrate has

been proposed. By using this method, uniform and smooth magnetic wires of very narrow patterns of 45nm in width can be fabricated. Moreover, uniform magnetic domains can be recorded on it by using magnetic head, and confirmed the uniform recording image by using a scanning TMR head.

IV. REFERENCES [1] D-T Ngo, K. Ikeda, and H. Awano, “Direct observation of domain wall induced by low-current density in TbFeCo

wires”, Appl. Phys. Express, vol. 4, 093002 (2011). [2] Do Bang, and Hiroyuki Awano, “Current-induced domain wall motion in perpendicular magnetizied TbFeCo wire

with different interface structure,” Appl. Phys. Express, vol. 5, 125201 (2012). [3] Do Bang, and Hiroyuki Awano, “Field- and Current-Induced Domain Wall Motion in Tb/Co Multilayers in the

Presence of Spin-Orbit Coupling-Induced Torques,” IEEE Trans. Magn., vol. 50, No. 11, p. 1401704, (2014). [4] Hiroyuki Awano, “Investigation of domain wall motion in RE-TM magnetic wire towards a current driven memory

and logic,” J. Magn. Magn. Mater., vol. 383, pp. 50-51, (2015). V. ACKNOWLEDGEMENTS

This work was partly supported by the Strategic Infrastructure Project of the Ministry of Education, Culture, Sports, Science and Technology, Japan, and JSPS KAKENHI Grannt Number 24360126, and 26630137.

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Ferromagnetic resonance for CoPt-based granular films with intergranular magnetic interaction

Shin Saito(a), Shintaro Hinata(a), (b), Daiji Hasegawa(a)

(a) Tohoku University, 6-6-05, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

(b) JSPS , Research Fellow (PD) e-mail: ssaito@ecei.tohoku.ac.jp

In current perpendicular magnetic recording, granular media consist of ferromagnetic

CoPtCr based magnetic grains and non magnetic oxide boundaries are used. To control 　static and dynamic magnetization process of the granular media, evaluation of intrinsic magnetic constants such as saturation magnetization (Ms), magnetic anisotropy field (Hk), gyro-magnetic ratio (γ), and damping constant (α) is quite essential. The ferromagnetic resonance (FMR), which is a resonance phenomenon of magnetic moments on effective fields, is one of the typical evaluation methods for Hk, γ, and α for a homogeneous material [1]. For the granular media, FMR signals thought to broaden due to distribution in magnetic properties and positions for each magnetic grain. However, its FMR signal was not significantly broader compared with that for alloy film with nearly the same composition for a Q band (~34 GHz) 　magnetic cavity method [2] (fig.1). In this study, the influences of intergranular magnetic coupling among columns, Hk distribution, and magnetic dipole interactions on FMR of the magnetic nano colum　 n which assume the granular media is investigated by numerical calculations based on the Landau Lifshitz Gilbert equation. In the case of 　 　grains with Hk distribution and no intergranular 　magnetic coupling, an FMR of assembly appears at an expected field based on the Kittel mode. This resonance had a long tail on the low magnetic field side (fig. 2). Such a resonance phenomenon is caused by a lot of coupling modes that originated from magnetic dipole interactions. In this case, α and Hk distribution can be evaluated from the full width at half maximum (FWHM) of the resonance and its long tail, respectively. On the other hand, the long tail reduced with increasing intergranular magnetic coupling. In this case, FWHM related to only α. This indicates that the resonance changed from the incoherent mode to a state near the Kittel mode, because of the increase in intergranular magnetic coupling even though there was distribution of Hk in the magnetic grains. [1] C. Kittel, Phys. Rev., 73, 155 (1948). [2] S. Hinata, et al., J. Appl. Phys., 111, 07B722-1 (2011).

Fig. 1 FMR signals for CoPtCr alloy film and CoPtCrSiO2 granular film.

0 2 4 6 8 10

FM

R s

igna

l (a.

u.)

HDCext (kOe)

Co76Pt16Cr8

Co74Pt16Cr108mol (SiO2)

Fig. 2 Calculated FMR signals for the magnetic grains with various Hk and inter-granular exchange coupling of 0 erg/cm3.

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Microstructure and magnetic properties of FePt film with carbide intermediate layer

Jai-Lin Tsai, Jie-Lin Tzeng, Keng-Chun Hu, Hsu-Kang Li, Zu-Yu Pan, Yuan-Shuo Chang, Chang-Chun Liao

Department of Materials Science and Engineering, National Chung Hsing

University, Taichung 402, Taiwan e-mail: tsaijl@dragon.nchu.edu.tw

The L10 FePt thin film is a promising material for heat assisted magnetic recording

(HAMR). To achieve high (001) texture and perpendicular magnetic anisotropy, the

FePt film was almost prepared on MgO, TiN/CrRu intermediate/seed layers. In this

work, the group 4-6d transition metal-carbide, for example MoC, TiC(O), TaC, were

used as the epitaxial intermediate layers of FePt film. The Mo, Ta, Ti-carbide with near

equal atomic ratio shows face centered cubic structure with a lattice constant similar to

MgO (~0.42 nm). The (200) textured MoC [1], TaC, and TiC(O) films were prepared

by magnetron sputtering on CrRu(200)/[110]/glass with small lattice misfit (~3.5%).

From x-ray diffraction patterns (XRD), the TaC (200) peak shows much higher relative

intensity than TiC(O) and MoC and the TaC (200) diffraction peak was shifted to lower

angle as compared to MoC (200). Furthermore, the L10 FePt film was deposited on

TaC, TiC(O) or MoC intermediate layer at 425oC. The FePt films illustrates (001)

texture on TaC, TiC(O) and MoC intermediate layer but the ordering degree are quite

different. The ordering degree effects on magnetic anisotropy and microstructure were

further discussed.

[1] Jai-Lin Tsai, Qi-Shao Luo, Po-Ran Chen, Yun-Ting Tseng, J. Magn. Magn. Mater.

382 (2015) 335-341

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DC-04

Altering coercivity via various growth rate on domain wall pinning (001) FePd thin film

C. H. Hsiao, and Chuenhou (Hao) Ouyang

Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

e-mail: houyang@mx.nthu.edu.tw

High magnetic anisotropy (1.7107 erg/cc) FePd films grown on MgO(100)

substrates with perpendicular magnetic anisotropy fabricated by electron beam

deposition system, have been demonstrated. Stacking faults induced by strain

relaxation, which act as strong domain wall pinning sites during magnetization reversal

are closely related to out-of-plane coercivity (Hc,) of (001) oriented FePd films

prepared at various temperatures. Through climbing dissociation of total dislocation,

the stacking fault density (S.F.) is promoted (1.22 nm-2), resulting in distinguished

promotion in Hc, (6000 Oe) as prepared at 650 oC with grwoth rate of 0.01 Å/s[1].

Therefore, Hc, of FePd films could be manipulated via adjusting S.F. through

manuplating growth rate. FePd films with growth rate altering from 0.005 to 0.03 Å/s

is carriedd out at 600 oC. Hc, drops significantly by raising or decreasing growth rate,

indicating S.F. is affected strongly by deposition parameters[2]. [1] C. H. Hsiao, Y. D. Yao, S. C. Lo, H. W. Chang, and Chuenhou (Hao) Ouyang, Applied Physics Letters,107, 142407 (2015);[2] C. T. Liu, R. W. Cahn and G. Sauthoff, Ordered Intermetallics - Physical Metallurgy and Mechanical Behaviour (Springer, 1991) , p. 138

B-177

DC-05

Microstructure and magnetic anisotropy of FePt thin film by rapid thermal annealing

Jin-Yan Chiou and Chuenhou(Hao) Ouyang

Department of Materials Science and Engineering, National Tsing Hua University,

Hsinchu 30013, Taiwan

Email : ken810304@gmail.com

Highly L10-ordered FePt thin films with a strong (001) texture were successfully fabricated on SiO2/Si substrates by sputtering and rapid thermal annealing. Fig. 1.shows the θ-2θ scans of XRD for FePt films on SiO2(90nm)//Si annealed at 550 with different heating rate and the related simulation of random directions. We can find that all the peaks are shifted to higher angle compared with the XRD simulation, this means FePt films were subjected to tensile stress. However, not only heating rate, but FePt composition is strongly dependent on (001) texture. Fig. 2. shows the different composition of FePt with heating rate of 40 /s. Only samples around stoichiometric composition of FePt have good (001)-orientation. Finally, we will discuss the microstructure of FePt thin film by High Resolution Transmission electron microscope. Fig. 3. show HRTEM of FePt thin film with heating rate of 60 /s. By comparing the local diffraction pattern obtained from FFT in FePt film with L10 ordered FePt simulated diffraction patterns, strong superlattice diffraction spots (001) with the magnetization easy axis [001] direction perpendicular to film plane were observed. This is consistent with perpendicular magnetic anisotropy property measured by XRD. In the future, we will discuss the relationship between magnetic properties and microstructure of FePt by rapid thermal annealing. To prove that magnetization process could be controlled by the heating condition.

Fig. 1 X-ray diffraction patterns for annealed FePt different heating rate and the XRD simulation.

Fig. 2. XRD patterns of FexPt1-x films annealed at 550oC for 10s with heating rate of 40oC/s. x=(a)62(b)58(c)54(d)50.

Fig. 3. (a) Cross-sectional HRTEM of FePt thin film with the heating rate of 60oC/s.(b)simulated diffr- action pattern and FFT

B-178

PJ-01

Fig. 1 The obtained effective fields

at different current densities. The

inset shows the calculated Oersted

field.

Characterization of the field-like term of spin-orbit

torque in Ta/Co/Pt by sweeping transverse field

Feilong Luo, Sarjoosing Goolaup, Sihua Li, Gerard Joseph Lim, Funan Tan, Christian Engel, Fusheng Ma, Wen Siang Lew

School of Physical and Mathematical Sciences, Nanyang Technological University, 21

Nanyang Link, Singapore 637371

E-mail: wensiang@ntu.edu.sg

The measurement of field-like term of spin-orbit torque (SOT), which results

from interface Rashba effect in heavy metal/ferromagnetic material (HM/FM), can be

carried out using the harmonic measurement technique. However, most of the

measurements have been carried out in ultra-thin HM/FM films with interfacial

perpendicular magnetic anisotropy (PMA). In HM/FM systems with in-plane magnetic

anisotropy (IMA), the interfacial anisotropy is negligible. To understand the origin of

the interface Rashba effect, it is imperative to study HM/FM films with IMA. Recent

studies on SOT in IMA films have reported that an in-plane transverse field sweep does

not provide information of the field-like term similar to PMA systems [1]. Here, we

theoretically and experimentally show that

the field-like term in IMA system can be

obtained by the in-plane transverse field

sweep. Figure 1 shows the experimentally

measured field-like term of SOT in IMA

system which is obtained by the in-plane

transverse field sweep. The results are

consistent with the values reported in

literature, where PMA is chosen.

[1] M. Hayashi, J. Kim, M. Yamanouchi

and H. Ohno, Phys. Rev. B 89, 144425 (2

014).

B-179

PJ-02

Voltage-controlled magnetic anisotropy in an ultrathin

Fe layer sandwiched between Cr and MgO layers

Takayuki Nozaki(a), Anna Kozioł-Rachwał (a),(b), Witold Skowroński(a),(b), Vadym Zayets(a), Yoichi Shiota(a), Shingo Tamaru(a), Hitoshi Kubota(a),

Akio Fukushima(a), Shinji Yuasa(a), and Yoshishige Suzuki(a), (c)

(a)National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki, Japan

(b)AGH University, Al. Mickiewicza 30, 30-059 Krakow, Poland (c) Osaka University, Toyonaka, Osaka, Japan

e-mail: nozaki-t@aist.go.jp

Voltage-controlled magnetic anisotropy (VCMA) is increasingly gaining attention as a promising approach for low power manipulation method of spin [1]. The VCMA effect originates from voltage-induced charge accumulation/depletion at the interface of ultrathin ferromagnetic metal and insulative layers, such as in MgO-based magnetic tunnel junction (MTJ). One of the most important technical challenges for the VCMA effect is the scalability issue. For example, for G-bit class memory applications, high VCMA coefficient of more than 1000 fJ/Vm is demanded. However, the demonstrated VCMA effect with high speed response is limited to be only 100 fJ/Vm at present [2].

In this study, we investigated the VCMA effect in an ultrathin epitaxial Fe layer sandwiched between Cr buffer and MgO barrier layers. Fully epitaxial magnetic tunnel junctions of Cr(30 nm)/ultrathin Fe (tFe)/MgO(2.3-2.8 nm)/Fe(10 nm) were deposited on MgO(001) substrates by molecular beam epitaxy. The VCMA effect in the ultrathin Fe free layer was evaluated from bias voltage dependence of TMR curves measured under in-plane magnetic field applications using the orthogonal magnetization configuration between free and reference layers [2]. Figure 1 shows an example of applied electric-field dependence of surface anisotropy energy, KperptFe for the MTJ with tFe=0.45 nm. We observed large VCMA coefficient of about 400 fJ/Vm with strong non-linearity.

This work was partly supported by ImPACT

Program of Council for Science, Technology and a

Grants-in-Aid for Scientific Research (26709046).

[1] T. Maruyama et al., Nat. Mater. 4, 158 (2009)

[2] T. Nozaki et al. Appl. Phys. Exp. 7, 073002 (2014).

Fig. 1 Applied electric-field

dependence of the surface

anisotropy energy observed in a

Cr/ultrathin Fe/MgO/Fe MTJ.

-300 -200 -100 0 100 200 3000.32

0.36

0.40

0.44

0.48

0.52

Kpe

rpt F

e (m

J/m

2 )

Electric field (mV/nm)

B-180

PJ-03

Curvature induced spin accumulation

Z.B. Siu(a), M.B.A. Jalil(a) and S.G. Tan(b) (a) National University of Singapore, Singapore

(b) Data Storage Institute, Singapore

e-mail : elesiuz@nus.edu.sg The coupling between the spin and momentum degrees of freedom due to Spin

Orbit Interactions (SOI) allows the control of one degree of freedom to manipulate the other. For example, the momentum of the charge carriers can be modified by introducing geometric curvature into the waveguides. Aspects of the influence of curvature on spin accumulation have been studied by various authors [1]. In this work, we show via two distinct techniques that curvature in SOI systems leads to the generation of spin polarization perpendicular to the plane of motion.

In the first approach, we adapt an adiabatic approach first used by some of us to explain the emergence of out-of-plane spin polarization in the Spin Hall Effect (SHE) [2]. We show analytically that the change in momentum direction due to the curvature in a waveguide lying flat on the xy plane has an analogous effect to the acceleration of the charge carriers due to the electric field in the SHE and imparts an out-of-plane accumulation. In the second approach, we exploit the fact that the observable quantities calculated for the eigenstates of a time-independent Hamiltonian do not vary in time. The Heisenberg equations of motions (EOMs) for the time evolution of these observables hence constrains the combination of observables that appear in the EOMs to add up to 0. We show that these constraints predict the existence of finite out-of-plane spin accumulation for a asymmetrically curved waveguide that does not lie flat on the xy plane.

We perform numerical calculations to verify our analytic predictions. The figure shows some exemplary results from the numerical calculations.

Panel (a) shows the out-of-plane spin accumulation in a sinusoidal waveguide with Rashba SOI lying on the plane, and (b) the spin accumulation (indicated by red arrows) and charge density on a waveguide of infinite length in the z direction. [1] M-H Liu and C-R Chang, Phys. Rev. B 74, 195314 (2006); M-H Liu et al, Phys. Rev. B 84, 085307 (2011). [2] T. Fujita, M.B.A. Jalil and S.G. Tan, New J. Phys. 12, 013016 (2010); S.G. Tan and M.B.A. Jalil, J. Phys, Soc. Jpn. 82, 094714 (2013).

B-181

PJ-04

Effective Hamiltonian for Topological Insulator Nanotubes

Z.B. Siu(a), M.B.A. Jalil(a) and S.G. Tan(b)

(a) National University of Singapore, Singapore

(b) Data Storage Institute, Singapore e-mail : elesiuz@nus.edu.sg

In this work, we derive the effective Hamiltonian for the surface states of a

hollow topological insulator (TI) nanotube. Similar to the more widely studied TI thin films [1] which possess both upper as well as lower surfaces, a hollow TI nanotube has both an inner as well as an outer surface. Each of these surfaces support surface states localized near the surface boundaries. The states on each surface hybridize with the states on the other surface due to the finite thickness.

The TI nanotube differs from the TI thin film in two important aspects. Firstly, there exists an intrinsic asymmetry between the inner and the outer surfaces due to the difference between the inner and outer radius. Second, the effective spin orbit interaction (SOI) field experienced by the TI surface state is perpendicular to both the momentum as well as the surface normal. The surface normal, which points along the radial direction on a nanotube, changes direction as we traverse the circumference of the circular cross section of the nanotube. Both the resulting position dependence of the SOI field, as well as the asymmetry between the inner and outer radius of the nanotube, result in the emergence of many more terms in the effective Hamiltonian of the TI nanotube compared to the TI thin film. Starting from a 4-band Hamiltonian [2] describing both the bulk as well as the surface states of a TI and adopting the procedures from Ref. [1], the Hamiltonian for a TI cylinder in standard cylindrical coordinates is derived to take the form of

where the s represent the real spin, the s an orbital degree of freedom, and the s, s and s are parameters dependent on the dimensions of the nanotube.

The signs of some of these parameters switch with the variation of the inner and outer radius of the tube. This leads to markedly different behavior, for example the sign of the Hall conductivity, for the lowest energy eigenstates for tubes of different dimensions. [1] C-X Liu et al, Phys. Rev. B 81, 041307 (2010); H-Z Lu et al, Phys. Rev. B 81, 115406 (2010). [2] C-X Liu et al, Phys. Rev. B 82, 045122 (2010).

B-182

PJ-05

Magnetic Phase Transition of La1-xSrxMnO3 Induced by

Charge Transfer and Interdiffusion

Angus Huang (a), Ching-Hao Chang (b)*, Horng-Tay Jeng(a), (c)**

(a) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (b) Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrae 20

Dresden, 01069, Germany (c) Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

*e-mail: cutygo@gmail.com **e-mail: jeng@phys.nthu.edu.tw

Rare earth manganites under hole doping: R1-xBxMnO3 (R = La, Nd, Pr and B = Sr, Ca,

Ba) attract intensive attention in recent years because of the rich

carrier-temperature-magnetism phase diagram. More importantly, these phases are

tunable by applying external conditions such as strains and/or boundary conditions.

For example, the ferromagnetic phase dominated by the double exchange mechanism

can be transferred to antiferromagnetic phases by controlling the doping levels. In this

work, by using first principles calculations based on DFT, we study the bilayer system:

La0.68Sr0.33MnO3 (LSMO)/ SrRuO3(SRO) combining two ferromagnetic materials. We

demonstrate that the original ferromagnetism in LSMO turn to A-type

antiferromagnetism, which is consistent with recent experiments. Such magnetism

stems from that the coexisting interdiffusion and charge transfer from the SRO layer

results in the LSMO/SRO interface analog to the hole-doped LSMO layer attached on

a substrate with electric polarization, indicating the intriguing behavior at the

transition-metal oxides interface.

B-183

PJ-06

Controllable Synthesis of Porous Fe3O4 Nanospheres

and Their Application to Electromagnetic Wave Absorption

Rambabu Kuchi(a), Viet Dongquoc(b), Jong-Ryul Jeong(a) (b)*

(a)(b)Department of Materials Science and Engineering, Graduate School of Energy

Science and Technology, Chungnam National University, Daejeon 305-764, Korea

Email: rambabu.kuchi@gmail.com

Porous magnetite (Fe3O4) nanospheres (PMNS) composed of primary spherical

nanocrystals have been successfully prepared via one-step solvothermal method with

gas-bubble template. To understand the formation mechanism, the reaction parameters

such as the concentration of precursor, precipitating agent, capping agent (PVP), and

gas source were investigated by fixing the reaction temperature and time. The

characterization of the as prepared product was identified with field emission scanning

electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray

diffraction (XRD), vibrating sample magnetometer (VSM) and N2

adsorption-desorption technique. The results indicate that the primary spherical

nanocrystals size was controllable by regulating the urea concentration. For further

application, these nanospheres were mixing with paraffin wax and studied their

electromagnetic properties. We found that urea plays an important role to control

primary nanospheres size and the porosity of the final spheres. The electromagnetic

properties measurements, high porous magnetite spheres showed the maximum

reflection loss (RL). A maximum reflection loss (RL) of the highly porous spheres can

reach -28.31 dB at 12.2 GHz with a thickness of 2.7 mm due to an improved

impedance matching that is associated with complex permittivity, complex

permeability, and the structure of the material. We believe the prepared porous Fe3O4

nanospheres can be good candidates for electromagnetic absorbing materials.

B-184

PJ-07

Effect of co-doping on the magnetic and electronic properties of multiferroic Y1-yDyyMn1-xFexO3

L.P. Yang(a), A.M. Zhang(a)#, Y. Dai(a), Z.R. Gao(a) and X.S. Wu(b)

(a)College of Science, Hohai University, Nanjing 210098, China (b)National Laboratory of Solid State Microstructures & Department of Physics,

Nanjing University, Nanjing 210093, China

Recent years, multiferroic materials have attracted extensive interest for the

coexistence of ferroelectric and magnetic orderings. The hexagonal YMnO3 is a

geometry frustrated system with a ferroelectric transition at TC=914 K and

antiferromagnetic order below TN=80 K. In the present work, polycrystalline samples

YMn1-xFexO3 (x=0.1-0.5) and Y1-yDyyMn0.5Fe0.5O3 (y=0.1, 0.2) were synthesized by

solid state reaction method. Microstructures, magnetic and dielectric of Fe-Dy

co-doped YMnO3 samples were comparatively investigated. Phase purity and

microstructures of the samples was characterized by powder X-ray diffraction (XRD)

in the angular range 15o≤2θ≤90°at room temperature. Local electronic structure of

constituent atoms of the samples was studied using X-ray photoemission spectroscopy

(XPS). Structure of the samples changes from hexagonal to orthorhombic phase with

doping content x increasing. A single hexagonal phase has been observed for

YMn1-xFexO3 for x≤0.3 based on Rietveld refinement. Hexagonal phase and

orthorhombic phase coexist for YMn1-xFexO3 for x>0.3. The XPS spectrum indicated

that the valence state of Fe in these samples is purely +3. The temperature dependence

of magnetization presents that the magnetic moment at low temperature increases with

increasing the doping concentration of x. Meanwhile, spin-glass feather is found to

become more and more obvious. The dielectric at low temperature were measured by

Impedance/Gain phase analyzer (HP 4194A). The anomalous dielectric peaks

observed around TN in these samples indicate the coupling between electric and

magnetic order parameters. The detailed structural, magnetic and dielectric properties

are discussed in detail.

B-185

PJ-08

Periodic Gate Voltage on the Magnetic Tunneling Junction

Sui-Pin Chen

Department of Electrophysics, National Chiayi University, Chia Yi, Taiwan e-mail: spchen@mail.ncyu.edu.tw

The spin-dependent tunnelling (SDT) from the coupling between magnetism and

electronic transport properties is one of richest veins of research both for the depth of

fundamental phenomena available and for the potential and proven applications [1]-[4].

One of the most important device structure is the magnetic tunneling junction (MTJ).

An MTJ consists of an FM1-I2-FM3 structure, where FM1 and FM3 are ferromagnetic

electrodes and I2 is a thin insulator. The key functional feature of the SDT in an MTJ is

the so-called tunneling magnetoresistance (TMR) ratio, the difference in resistance

when the magnetizations of two electrodes are aligned parallel or antiparallel. Here,

we apply the spin-polarized free-electron model and use the transfer matrix method to

study the TMR ratio in a MTJ [1][2]. Unlike the traditional method of varying the

magnetizations configuration between the two ferromagnetic layers, the proposed

method uses the periodic gate voltage on the insulator I2 to change the TMR in the

FM1-I2-FM3 MTJ. The gate voltage is sine-type. Its amplitude can be tuned. Under

suitable conditions, we find that the TMR change resulting from the periodic gate

voltage is larger than that in a conventional method of varying the magnetizations

configuration in the MTJ and that the magnitude of this effect originates from the

resonant tunneling. [1] J. C. Slonczewski, Physical Review B, 39, 6995 (1989).

[2] S.-P. Chen, Journal of Applied Physics, 107, 09C716 (2010).

[3]S. Yuasa, T. Nagahama and Y. Suzuki, Science, 297, 234 (2002). [4] J. D. Burton and Evgeny Y. Tsymbal, Physical Review B, 93, 024419 (2016).

B-186

PJ-09

Flip-Flop SR Latch and Half-Adder Logic Circuit Configurations using SOT-MTJ

D.J.J. LOY, S. GOOLAUP, W.S. LEW

School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore, Singapore

e-mails: dloy001@e.ntu.edu.sg, sgoolaup, wensiang@ntu.edu.sg

We present SPICE simulation results of a novel Flip-Flop SR Latch and Half-Adder

logic that operates at faster switching times and lower switching energies. Spin orbit

torque (SOT)-magnetic tunnel junctions (MTJs) are suitable for logic operations due to

its ability to isolate its read and write paths as well as other properties such as

non-volatility and scalability. In this work we propose and demonstrate SOT-MTJ

based spin logic architectures using SPICE. A Half-Adder and SR-Latch structure

constructed using SOT-MTJs in a circuit configuration are tested. Our circuits have

been found to require lesser devices (transistors), faster switching times and lower

switching energies as compared to its conventional semiconductor counterparts. The

results are summarized in Tables 1 & 2. Table 1. Comparisons between 180nm CMOS, Carbon Nanotube Field Effect Transistor (CNFET) and SPICE SOT-MTJ model for a Flip Flop SR-latch logic.

Device/Model Switching Time (ps) Energy Delay (10-24 J-s)180nm CMOS 160 6.77

CNFET [1] 14.4 7 x 10-4

SPICE SOT-MTJ 1.02 4.1 x 10-6

Table 2. Comparisons between 180nm CMOS Gate diffusion Input (GDI), 180nm CMOS MUH and SPICE SOT-MTJ model for a Half-Adder logic.

Device/Model Switching Time (ps) Energy Delay (10-24 J-s)180nm CMOS (GDI) [2] 48.25 2.56 x 10-2

180nm CMOS (MUH) [2] 34.9 1.27 x 10-2

SPICE SOT-MTJ 1.02 8.69 x 10-6

[1] C. Dwyer, M. Cheung and D. J. Sorin, “Semi-empirical SPICE Models for Carbon Nanotube FET Logic,” in Fourth IEEE Conference on Nanotechnology, Munich, Germany, August 17-19, 2004.

[2] M. Sadeghi and A. Golmakani, “Two New Topologies for Low-Power Half-Adder in 180nm CMOS Technology,” World Applied Sciences Journal, vol. 31, no. 12, pp. 2057-2061, 2014.

B-187

PJ-10

Electric Field-Induced Magnetic Anisotropy Change for

Fe-Pt-Pd Alloys Satoru Kikushima(a), Takeshi Seki(a), Ken-ichi Uchida(a)(b), Eiji

Saitoh(a)(c)(d)(e), Koki Takanashi(a) (a)Institute for Materials Research, Tohoku University, Sendai, Japan

(b)PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan (c)Spin Quantum Rectification Project, ERATO, Japan Science and Technology

Agency, Sendai 980-8577, Japan (d)WPI Advanced Institute for Materials Research, Tohoku University, Sendai

980-8577, Japan (e)Advanced Science Research Center, Japan Atomic Energy Agency, Tokai

319-1195, Japan e-mail: satoru_kikushima@imr.tohoku.ac.jp

Recently, to reduce the energy consumption is a crucial issue. In the field of electronics, magnetic storage devices such as magnetic random access memory (MRAM) have attracted much attention because its non-volatility leads to low power consumption during the data storage. However, large external power is required in order to write information onto magnetic bits. For example, spin transfer torque (STT) or a magnetic field generated by current flow is used to switch the magnetization direction. One of the methods for magnetization switching with low external power is to use an electric field effect because it does not require the electric current flow.

Since L10-ordered FePt and FePd have large uniaxial anisotropy energy, these materials are suitable for ultrahigh density MRAM owing to the excellent thermal stability of magnetization in a nanometer region. However, the magnetic anisotropy energy change by electric field application was not large enough for the practical use [1]. Also, the detail mechanism of electric field effect has not been understood yet. In this study, in order to enhance the effect of electric field on the magnetic anisotropy, we systematically investigated the electric field effect on the magnetic anisotropy for the Fe-Pt-Pd systems.

Thin films were prepared employing ultrahigh vacuum sputtering and electron beam evaporation. The Fe-Pt-Pd ultrathin layers were grown on an MgO (100) substrate with a Pd buffer layer. The magnetic properties were measured using a polar magneto-optical kerr effect (MOKE) and a superconducting quantum interference device (SQUID). For the experiment of voltage application, the devices were fabricated through the use of photo-lithography and Ar ion etching. The polar-MOKE loops were measured with electric field applied to evaluate the electric field-induced perpendicular magnetic anisotropy change per area (perpt)

When the FePt layer was deposited at 400ºC, the FePt layer had perpendicular magnetic anisotropy but its polar-MOKE loop showed low squareness. In the case of FePt, the perpendicular magnetic anisotropy was decreased when the positive electric field (E) was applied in which the electrons were accumulated at the FePt surface. The value of perpt/ E was obtained to be 139 (fJ/Vm). The magnitude of electric field effect was decreased as the Pd concentration was increased in the Fe-Pt-Pd, and the small electric field-induced coercivity change was observed for the FePd layer.

[1] M. Weisheit, et.al., SCIENCE, 315, 19 (2011).

B-188

PK-01

Spin Transport Properties of Amine-ended Single-Molecule Magnetic Junctions

Kuan-Rong Chiang, Chia-Jung Lin, Yu-Hui Tang*

Department of Physics, National Central University, Jhong-Li, Taoyuan, Taiwan

e-mail: yhtang@cc.ncu.edu.tw

The manipulation of spin transport properties in FM/single molecule/FM junctions

has attracted intensive attentions due to their potential applications in molecular spin

electronics, where FM denotes the ferromagnetic materials. Recently, the

first-principle method with the non-equilibrium Green's function approach has been

successfully employed to study the conductance switching properties during the

stretching [1] of Au/single molecule/Au junctions, which agree well with the

experimental observations [2], and the strain-enhanced spin injection in amine-ended

single-molecule magnetic junction. [3] The underlying mechanism can be understood

by the hard and soft and acid and bases (HSAB) theory and the novel spinterface effect

[4]. The former domains the stability of bond between atoms; the latter shows how

interface geometry affect the spin properties in this motif.

In this study, two different central molecules, π-saturated Benzenediamine (BDA)

and σ-saturated Alkanediamine (ADA), by using dissociated amine linkers to mediate

two semi-infinite Co electrodes under stretching process, can be employed to simulate

the experimental breaking junction techniques. Comparing the σ-saturated ADA

junction, we expect that the more conductive π-saturated BDA may provide better

spin-injection from ferromagnetic Co electrodes and then give rise to large

spin-polarized current densities. Moreover, the effect of mechanical strain on the spin

transport property may provide useful information to the future single-molecule

spintronics devices. (Contract No. NSC 102-2112-M-008-004-MY3) [1] Y. –H. Tang et al., J. Phys. Chem. C 115, 25105 (2011)

[2] B. Q. Xu et al., Nano Lett. 5, 1491 (2005)

[3] Y. –H. Tang et al., J. Phys. Chem. C 120, 692 (2016)

[4] S. Sanvito., Nature. Phys. 6, 615(2010)

B-189

PK-02

Study of the Formation and Switching Behaviour of

Domain Wall in Permalloy Thin Film Rings

Kao-Fan Lai, Li-Hao Chan, Deng-Shiang Shiu, and Lance Horng

Department of Physics, National Changhua University of Education, Changhua, Taiwan

e-mail: phlhorng@cc.ncue.edu.tw

Formation of domain wall can reduce interaction of the stray field between the

magnetic devices.[1] The device can be stable for storage information.[2] Therefore,

we observed the behavior of moments by simulation software OOMMF with different

outer diameter and thickness, and we found the faster method of generation or

destruction 360 degree domain wall by manipulating magnetic field.[3] In this study,

we found that the 360 degree domain wall cannot be generated when the thickness is

above 10 nm. There was more space on z-axis to release the domain wall energy. We

made samples by using the e-beam lithography technology and magnetron sputtering.

We observed the magnetic domain with dark and bright specific in the magnetic ring

devices figured by the magnetic force microscope.

[1] Yu-feng Hou and Kannan M. Krishnan, Journal of Applied Physics, 111, 07B905

(2012).

[2] Ahmet S. Demiray, Tetsuya Miyawaki, Yusuke Watanabe, Makoto Kohda, Kesami

Saito, Seiji Mitani, Koki Takanashi, and Junsaku Nitta, Japanese Journal of Applied

Physics, 51, 04DM04 (2012).

[3] Andrew Kunz, Applied Physics Letters, 94, 132502 (2009).

B-190

PK-03

Aspect ratio dependence of ferromagnetic resonance in thin film ellipse arrays

C. H. Li(a), Z. W. Fan(b), Y. G. Yang(b), H. T. Huang(a), and Z. Wei(a) (a)Institute of NanoEngineering and MicroSystems, National Tsing Hua University,

Hsinchu 30013, Taiwan (b)Regional R&D Services Department, Metal Industries Research and

Development Centre, Taichung 407, Taiwan e-mail: vfande245@hotmail.com

This report investigates ferromagnetic resonance of elliptical magnetic films which have different aspect ratio at different dc magnetic field. We utilized photolithography techniques and photo mask to transfer the elliptical array pattern to a glass substrate. Then samples were evaporated Permalloy thin film (Ni81Fe19) by e-gun evaporation system. After lift-off procedure, we acquire elliptical Permalloy arrays on the glass substrate. All minor axes of elliptical arrays are 7.5 μm, and edge-to-edge distance is 4 μm. The aspect ratios of different elliptical arrays gradually change from 1:1 (circular array) to 1:4.

We utilize microstrip to measure the ferromagnetic resonance of ellipse arrays. During measurements, the dc magnetic fields are applied along the major axis, and the alternating magnetic field (Hrf) perturb along the minor axis direction.

Figure 1 shows the ferromagnetic resonance frequency of different aspect ratio elliptical arrays in the different dc magnetic field. When the dc magnetic fields are getting larger, the frequency of ferromagnetic resonance moves toward higher frequency. The larger aspect ratio of elliptical array also reveals higher ferromagnetic resonance frequency. The ferromagnetic resonance frequency of circular array is the lowest. In Fig. 2, the aspect ratio of elliptical array is 1:4. It can be observed that the ferromagnetic resonance frequency will be split into two parts when the applied dc magnetic fields sweep down to smaller. This phenomenon suggests that the elliptical magnetic film in the small dc magnetic field may be generated different magnetization statement.

Fig. 1. The ferromagnetic resonance

frequency of different aspect ratio elliptical

arrays in the different dc magnetic field.

Fig. 2. The ferromagnetic resonance

frequency of elliptical aspect ratio 1:4 in

small dc magnetic field.

B-191

PK-04

Thermoelectric property of ferromagnetic nanowire enhanced by substrate roughness

S. H. Wang(a), H. T. Huang(b), and Z. Wei(b)

(a)Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan

(b)Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

e-mail: vfande245@hotmail.com We studied the thermoelectric effect of Ni nanowires with various degrees of surface

roughness. In this study, as we can see in the figure, the red area in the left of the figure 1(a) is the heating source provided by electrical current while the blue area on the right-hand-side of the figure is kept at substrate temperature, this will generate a temperature gradient on the Ni nanowire. The larger the electrical current, the larger the temperature differential between two ends of the nanowire. The thermo voltage can be measured by the electrodes on the top of the figure 1(a). Figures 1(b) to (e) respectively show the SEM images of the Ni nanowire with heavy, moderate, minor and no surface roughness. Figure 2 shows that the larger the heating power, the larger the thermal voltage generated by thermoelectric effect. Also, heavier surface roughness leads to larger thermal voltage. As for the magnetic field’s part in this experiment, we determine that the thermoelectric effect can be enhanced by applying a 2500 Gauss magnetic field, we believe this is due to the magnetic torque is pinned by the external field, therefore hindering the heat conduction and at the same time, enhancing the thermoelectric effect.

Fig. 1(a) SEM image of the Ni nanowire thermoelectric device, 1(b)-(e) Ni nanowires

with different degrees of surface roughness.

Fig. 2(a) Thermal voltage of different degrees of surface roughness. (b) Thermal

voltage of different magnitude of magnetization.

B-192

PK-05

0 50 100 150 200 250 3000

100

200

300

400

5000

20

40

60

10nm 20nm 30nm 40nm 50nm 70nm

(

-cm

)

T (K)

M (

emu

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FC, H=100 Oe

Strain effects on magnetic Sm0.67Sr0.33MnO3 thin films

S. L. Cheng,(a,b) T. H. Chuang,(a) and J. G. Lin (b)

(a)Departmen of Materials Science and Engineering, National Taiwan University (b) Center for Condensed Matter Sciences, National Taiwan University,

Taipei,10617,Taiwan e-mail: jglin@ntu.edu.tw

The perovskite manganese oxides have been extensively investigated due to their

intriguing phenomena such as colossal magnetoresistance (CMR) and insultor-metallice transitions. The CMR was first discovered in La0.67Ca0.33MnO3 (ABO3) thin film with a ferromagnetic (FM) state of wide eg-band. Its bandwidth (W) plays an important role on the conduction mechanism and is strongly correlated with the lattice distortion of MnO6 octahedral which could be modified by changing the radius of A-site ions. The decrease of W follows the decrease of A-site radius until the competing interactions against double exchange become important, including collective Jahn-Teller distortion, antiferromagnetic interaction between two t2g spins, and charge/orbital ordering. However, the correlation of conduction mechanism and magnetic properties in narrow bandwidth materials is much less explored. In this work, the narrow-banded ferromagnetic Sm0.67Sr0.33MnO3 (SSMO) thin films are fabricated on SrTiO3 substrate to study the effects of lattice distortion on electrical transport and magnetization. Temperature dependent resistivity () and magnetization (M) for SSMO films with different thickness are displayed in FIG. 1, showing the electrical transition temperature (TIM) of SSMO films is

increased with suppressing as thickness is reduced. In comparison with the data of magnetization and crystalline, we observe a strong coupling between lattice parameter and magnetic moment. The results are depicted in FIG.2. The details of experimental results will be discussed in our article.

FIG.1. and M-T curves for SSMO thin films. (left side)

FIG.2. thickness (t) dependent c-parameter, magnetic transition (Tcm), saturation moment at 10 K (M10K) and

insulator-metallic transition (TIM). (right side)

0 20 40 60 807.54

7.56

7.58

7.6055

60

65

700

20

40

6080

100

120

140

c (Å

)

t (nm)

Tcm

(K

)

M10

K (e

mu

/cm

3 )

TIM

(K

)

B-193

PK-06

Magnetic properties of NiFe permalloy films with

Co-doping

M.C. Chan(a)* , H.W. Chang(b) , D.W. Wei(a)

(a)Institute of Manufacturing Technology and Department of Mechanical Engineering, National Taipei University of Technology (Taipei Tech), Taipei 10608, Taiwan (b)Department of Applied Physics, Tunghai University, Taichung 407, Taiwan

Recently, NiFe (permalloy) alloy has became a popular material for MR heads,

field sensor, and spintronic devices applications due to good anisotropic magnetoresistance (AMR), large permeability (~100000), high saturation magnetization (10 kG) and very low coercivity (< 1 Oe). Therefore, the NiFe thin film has advantage of high sensitivity, lower energy loss and less cost. In this present study, NiFe is adopted as a basic material, and structure and magnetic properties of sputter-prepared NiFe films on Ta underlayer buffered SiO2/Si(100) substrates with different sputtering parameters are studied in order to optimize AMR ratio. The experimental results show that the MR ratio of NiFe is related to the crystalline of NiFe (111). To modify the sputtering pressures of Ta underlayer and NiFe film could well control the crystallinity, and thus optimize AMR ratio. In addition, AMR of Co-doped NiFe films is also studied. With the increase of Co content, AMR ratio is enhanced. The possible reason is that the entrance of Co into fcc-NiFe might strengthen the spin-orbital coupling and therefore enhance AMR ratio. This research suggests that appropriate control of sputtering parameters of Ta underlayer and NiFe film and Co-doping can enhance the AMR ratio of NiFe films.

B-194

PK-07

Exchange bias of MnPt/NiFe films with various ordering

degree of L10-MnPt

P.H. Pan(a)*, H.W. Change(a), C.R. Wang(a), Lance Horng(b)

(a)Department of Applied Physics, Tunghai University, Taichung, 407 Taiwan.

(b)Department of Physics, National Changhua University of Education, Changhua 500, Taiwan.

Exchange bias (EB), characterized by the shift of hysteresis loops originated from

the interaction between the ferromagnetic (FM) and antiferromagnetic (AFM) layers,

has been extensively investigated due to wide applications in advanced spintronic

devices and giant magnetoresistance heads. Various AFM materials with CuAu-I type

ordered FCT structure and high Neel temperatures, such as NiMn, MnPt, and MnPd

have been attracted much attention, especially for MnPt. In order to obtain

L10-ordering, heat treatment is needed. Due to high exchange anisotropy and relative

low annealing temperature, MnPt/NiFe bilayer becomes a commonly used EB system.

In this study, MnPt/NiFe films are prepared on SiO2/Si(100) substrates at room

temperature (RT) by sputtering at the external magnetic field of 1 kG induced NdFeB

sintered magnets. They are annealed at designated temperature of 250-350 oC for 2 hrs,

then cooling to RT at the applied magnetic field of 2 kOe in order to promote the

L10-ordering and formation of its AFM phase. X-ray diffraction results show that the

peak of MnPt shift to larger degree, indicating a gradual formation of L10 phase. No

exchange field (Hex) is observed in the as-deposited state due to paramagnetic FCC

phase. Interestingly, the exchange field (Hex) increases with L10-ordering degree turned

by annealing temperature. In this presentation, the microstructure and morphology of

interface between MnPt and NiFe related to the magnetic properties are also discussed.

B-195

PK-08

Multiferroic properties of BiFeO3(110) films on CoPt(111) electrode layer on glass substrates at reduced

temperatures

C.C. Liu*, H.W. Chang

Department of Applied Physics, Tunghai University, Taichung 407, Taiwan

BiFeO3 (BFO) with a perovskite structure, which possesses ferroelectric and

magnetic orderings at room temperature (RT), has attracted much attention for

potential applications in advanced spintronic and memory devices based on the

electric-magnetic couplings. [1-3] In order to facilitate these coupling, the use of

ferromagnetic (FM) bottom electrode to induce specific texture of BFO seems to be a

most direct way. In this study, BFO films are grown on FM CoPt(111) underlayer on

glass substrate by sputtering. In addition to serving as a FM bottom electrode,

CoPt(111) is also expected to reduce the formation temperature of BFO phase [3-4]. A

CoPt layer with optimized (111)-texture was used to grow high-quality BFO film.

Structure, ferroelectric, and magnetic properties of BiFeO3 (110) films grown on

10–50-nm-thick ferromagnetic CoPt(111) buffered glass substrate at 350–550 oC have

been studied. (110)-texture of BFO films is developed at the reduced temperature as

low as 400–550 oC, but isotropic orientation is found at higher temperature of 600 oC.

Low temperature deposition results in dense microstructure, fine grains, and smooth

surface morphology, which are favorable for applications. BFO(110) films on

CoPt(111) underlayer exhibit desired ferroelectric and magnetic properties. Electrical

polarization (2Pr) of 96–137 µC/cm2 and coercive field (Ec) of 495–618 kV/cm for

studied BFO (110) films are comparable to those grown on single crystal substrates.

Moreover, exchange bias between BFO and CoPt is observed after a field cooling from

370 oC to room temperature (RT) at 2 kOe. Large exchange bias field of 155 Oe at RT

and coercivity of 1631 Oe are obtained. The presented results provide useful

information for the applications based on electric-magnetic interactions. [1] M. Bibes et al., Nature Materials 7, 425 (2008). [2] J. Wang et al., Science 299, 1719 (2003). [3] H.W. Chang et al., Nano. Res. Lett. 7, 435 (2012). [4] S. Ryu et al., Appl. Phys. Lett. 95, 242902 (2009).

B-196

PK-09

Magnetic Domain Wall Transfer in Discrete Magnetic Nanodot Chains

M. Yang(a), H.-G. Piao(a,b), D.-H. Kim(b), L. Pan(a), and S.-C. Yu(b)*

(a) College of Science, China Three Gorges University, Yichang 443002, P. R. China (b) Department of Physics, Chungbuk National University, Cheongju 361-763,

South Korea e-mail: scyu@cbnu.ac.kr

Recent progress in veious nano-scale etching techniques enables us to confine and manipulate magnetic domain walls (DWs) inside patterned ferromagnetic nanostructures. Control and understanding of DW dynamic behaviors are essential for future realization of spintronic devices based on the soliton-like DW motion. In verious ferromagnetic nanowires, dynamic behaviours of the soliton-like DW have been numerically and experimentally proposed recently [1-3]. In nanowires, the DW isolatism during the DW propagation is significantly affected by the nanowire geometry and dimension. In particular, DW dynamic behaviors in nanowires are restricted by various effects such as onset, pinning, Walker breakdown and so on. In this work, we numerically investigated dynamic behaviours of soliton-like DWs in discrete magnetic nanodot chains as a dissipative system with change the strength of the driving magnetic field. Considering the feasibility of the experiment, the discrete magnetic nanodot chain has been arranged in L-shape, as show in Fig 1. In order to prevent the introduction of superfluous DW, special nanodots are made in both ends of the chain (see Fig 1). Under the magnetic field drive, we have found that the DW is transferred in the chain conditionally, which is ascribed to the fact that there exists a dipole-dipole interaction between adjacent nanodots. The interaction depends on the nanodot geometry and the depinning field, as indirectly shown in Fig.1(a). To find the mechanism, we systematically examined stepwise behaviors of the soliton-like DW propagation in this scheme with changes of the magnetic field strength and the nanodot geometry, as shown in Fig.1(b). [1] H.-G. Piao, H.-C. Choi, J.-H. Shim, D.-H. Kim, C.-Y. You, Appl. Phys. Lett. 99, 192512 (2011).

[2] K.-D. Lee, C.-Y. You, H.-S. Song, B.-G. Park, S.-C. Shin, Appl. Phys. Lett. 104, 052416 (2014).

[3] J.-S. Kim, M. A. Mawass, A. Bisig, et al., Nat. Commun. 5, 3429 (2014).

Fig.1 Geometry and dimension of discrete magnetic nanodot chains. (a) Geometric-dependent depinning field and

time-dependent magnetization states in each ferromagnetic nanoelement.

B-197

PK-10

Study of domain-wall motion by IrMn/CoFeB exchange bias in a magnetic wire

Yun Hong(a) , Deng-Shiang Shiu (a), Chi-Yang Lin (b), Kao-Fan Lai(a), Wu(a), Lance Horng(a)

(a)Department of Physics, National Changhua University of Education, Changhua,

Taiwan (b) Gaduate Institute Of Photonics, Department of Physics, National Changhua

University of Education, Changhua, Taiwan e-mail: phlhorng@cc.ncue.edu.tw

In this study, we generate a vortex DW (VDW) in a magnetic nanowire and study the

magnetization dynamics of the device. The VDW has chirality and polarity called

Skymine. VDWs also can be useful for logic devices [1]. It is important to control and

read the VDWs in magnetic wires. We employ exchange bias to control the DW

movement. The exchange bias is used to pin the domain wall in the magnetic wire.

Using crossed antiferromagnetic (AF) bars and ferromagnetic (F) wire we induce the

exchange bias to pin the domain wall [2]. The device is fabricated by e-beam

lithography and magnetron-sputtering. VDWs are observed by MOKE-microscope or

by MFM by pinning the DWs at the cross-points. The structure at crossing points are

Ta(20 nm)/NiFe(6 nm)/IrMn(10nm)/CoFeB(7 nm)/Ta(20 nm). The AF bars we design,

have four widths of ~ 1 μm, 1.5 μm, 2 μm and 2.5 μm, to determine the pinning fields

and we obtain the fields are as ~ 16.76, 19.76 and 21.31 Oe in different AF bars,

respectively. Here, we have demonstrated the that it has no acute effect on pinning

fields when we change the IrMn(10 nm)/CoFeB(7) into Ta(17 nm). As it is important

to know how to control the VDWs, we need to control the chirality of the VDWs and in

this regard we will utilize asymmetry pads. We will run micromagnetic simulation to

analyse the structure of the VDWs and determine the exchange bias which can assist

the polarity of vortex switching.

[1] Aakash Pushp, Timothy Phung, Charles Rettner, Brian P. Hughes, See-Hun Yang,

Luc Thomas and Stuart S. P. Parkin, Nat. Phys. 9, 505–511 (2013)

[2] I. Polenciuc, A. J. Vick, D. A. Allwood, T. J. Hayward, G. Vallejo-Fernandez, K.

O’Grady, and A. Hirohata, Appl. Phys. Lett. 102.162406 (2014)

B-198

PL-01

Study on the magnetic properties, thermal stability and

corrosion resistance of the recycled sintered Nd-Fe-B

magnets

X. T. Li, W. Q. Liu*, M. Yue, X. W. Yin, D. T. Zhang

College of Materials Science and Engineering, Beijing University of Technology,

Beijing 100124, PR China

e-mail: liuwq@bjut.edu.cn

The recycling of the waste Nd-Fe-B sintered magnets with good magnetic properties

is an important issue [1]. In this paper, the waste sintered Nd-Fe-B magnets on a large

scale up to 500 kg per batch were recycled to manufacture anisotropic sintered magnets

by combination of hydrogen decrepitation (HD) and alloying modification technique.

Magnetic properties, thermal stability and corrosion resistance of both the waste

magnets and recycled magnets were investigated. The recycled magnet exhibits

magnetic properties with remanence (Br) of 12.38 kGs, coercivity (Hci) of 24.89 kOe,

and maximum energy product [(BH)max] of 36.51 MGOe, respectively, which restores

99.2% of Br, 105.6% of Hci, and 98.6% of (BH)max of the waste magnets, respectively

(Fig.1). The remanence temperature coefficient (a) and coercivity temperature

coefficient (β) of the recycled magnets are -0.1155%/K and -0.5099%/K in the range of

288-423 K, respectively, which are comparative to those of the waste magnets. The

corrosion results show that the recycled magnets perform the same corrosion

mechanism and approximate corrosion rate compared to these of the waste magnet,

which indicate that the recycled magnets could meet the demand in industrial

application.

[1] M. Zakotnik, I. R. Harris, A. J. Williams, J. Alloys Compd., 450, 525 (2008)

Fig.1 Demagnetization curves of the original waste and the recycled sintered magnets.

B-199

PL-02

The mechanism of enhanced coercivity for the (Nd, Pr, Ce)-Fe-B magnet with dual main phases

Rui Han, Hongsheng Chen, Liwei Song, Minggang Zhu, Shengzhi Dong and Wei Li Division of Functional Material, Central Iron & Steel Research Institute, Beijing 100081, P.R.China

Email: harry1425@hotmail.com Magnets made from Nd-Fe-B alloys exhibit excellent properties, and are now widely used in

many fields. From the commercial standpoint, cheaper isostructural compounds with equal magnetic properties are always desired, so various isostructural R2Fe14B compounds were investigated and their properties analyzed [1-3]. In this paper, Ce (the most abundant and low cost rare-earth element) based (Pr, Nd, Ce)2Fe14B magnets are investigated. According to the dual main phase method, the dual-main-phased magnet A and the traditional sintered magnet B were prepared. As shown in figure 1, it can be seen that the coercivity and the rectangularity of magnet A are much higher than those of magnet B, while the values of remanence are almost the same. In contrast with magnet B with one single Curie temperature phase, it is evident that the magnet A possesses two Curie temperature phases. This result indicates that the matrix phases alloy (PrNd0.5Ce0.5)31(Fe,TM)68B1 and alloy (PrNd)31(Fe,TM)68B1 have not fully penetrated into each other during the sintering process. The results of applying the first-order reversal curves (FORC) diagram experimental method to analysis the magnetization processes (as shown in figure. 2). The FORC diagram for the dual-main-phased magnet A shows the existence of three exchange spring regions, while that of the single-phased magnet B reveals that only one exchange coupling occurs between the matrix particles. The enhanced coercivity of the magnet A is mainly due to the improved microstructure in the sintered process by the dual main phase method. A change in the microstructure occurred for magnet A, there are more triple-junction areas in the matrix phases. The liquid phase of Ce-riched phase has lower eutectic reaction temperature and better wetting characteristics than Nd-riched phase. Thus, it is notable that the wettability of the triple junction phases improves dramatically with Ce-contents increasing. As a result, the coercivity has been reported to be generated simultaneously with the formation of the fcc RE-rich phase due to the reduction of the exchange coupling between the matrix grains, which is consistent with the results of the FORC diagrams.

[1] Yan, C. J., Guo, S., Chen, R. J., Lee, D. and Yan, A. R. Chin. Phys. B 23, 107501, (2014).

[2] Pathak, A. K. et. al. Adv. mater.13, 201404892 (2015).

[3] Corfield, M. R., Harris, I. R. and Williams, A. J. J. Alloys. Comp. 463, 182 (2008).

FIG. 1 Demagnetization curves for the

as-sintered samples A (dual-main-phased

magnet) and B (single-phased magnet).

FIG. 2 The experimental FORC diagrams for

dual-main-phased magnet (A) and single-phased

magnet (B).

B-200

PL-03

Microstructure and Magnetic Properties of Nd Fe B

Material Fabricated by Selective Laser Melting

Kai Jyun Jhong * Wen His Lee

Selective Laser Melting (SLM) is a powder-based additive manufacturing

capable to produce parts layer-by-layer from a 3D CAD model. The aim of this

study is to adopt the selective laser melting techniques forNd Fe B material fabrication.

When Nd Fe B product made by the selective laser melting techniques instead of

compaction, the design flexibility magnetic product will be improved. This study

analyzed the effect of magnetic property with different parameters of SLM process and

design a magnetic product to check the efficiency as compare with existing

manufacturing process.

B-201

PL-04

Effect of the Gilbert damping constant on domain wall pinning in permanent magnets

K. Yamada, and Y. Nakatani

Graduate school of Informatics and Engineering,

University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan e-mail: nakatani@cs.uec.ac.jp

Recently, the research and development of high-efficiency motors have been carried

out due to spread electric vehicles. It is required the property of high coercivity in permanent magnets (i.e., hard magnets). In the hard magnets, the pinning of the propagation of magnetic domain wall (DW) at the grain boundary (GB) is considered as the origin of the coercivity [1-3]. In the analytical studies for the DW pinning field (Hpin) at the GB, the effect of the damping constant () is not taken into account. In this report, we investigate the effect of on Hpin by using micromagnetic simulations.

The one-dimensional micromagnetic model is used in simulations. The length of the calculation region is 1 m. The widths of GB (wb) is varied from 1 to 34 nm. Material parameters used in the simulation are Ms = 1.62 Kemu/cm3, exchange stiffness constant A =1.0 erg/ cm3, magnetocrystalline anisotropy constant K1= 3.26 Merg/cm3. In the GB, K1

’ = 0 is assumed. ranges from 1.0 to 0.01 in the magnet. The procedure of the simulation is as follow: (1) the DW is located at the distant of 500 nm from the GB. (2) the external magnetic field (Hext) is applied for the DW propagation. (3) the maximum Hext to pin the DW at the GB is defineed as Hpin.

Figure 1 shows simulation results of the effect of and wb on Hpin. In the case of 0.3 < < 1, Hpin is almost a constant. On the other hand, in the case of < 0.3, Hpin is decreased with decreasing . These results indicate that Hpin is affected on . From these results, we found that Hpin is decreased by decreasing in the hard magnet. [1] H.-R. Hilzinger and H. Kronmüller , Phys. Lett. A 51, 59 (1975). [2] R. Friedberg and D.J. Paul , Phys. Rev. Lett. 34, 1234 (1975). [3] H. Kronmüller, K.-D. Durst, and M. Sagawa, J. Magn. Magn. Mater. 74, 291 (1988).

Fig. 1 Effect of α and wb on Hpin.

B-202

PL-05

Coercivity enhancement in hot-deformed Nd2Fe14B-type magnets by doping low melting point alloys

Y. I. Lee, G. Y. Huang, C. W. Shih and W. C. Chang

Department of Physics, National Chung Cheng University, Chia-Yi, 621 Taiwan, ROC

e-mail: godlovercrown@gmail.com

Hot deformation Nd2Fe14B-type magnets have been reported as one of the ways to obtain high magnetic energy product in disc and cylindrical shapes. To date, the coercivity of hot-deformed magnet is normally less than 18 kOe at room temperature using Dy-free Nd2Fe14B MQU-F powders as a precursor. In order to widen the application of the hot deformation magnets for high operation temperature, doping low melting eutectic alloys with Nd2Fe14B MQU-F powders to improve the coercivity has been report in recent year.[1] The anisotropic NdFeB magnets prepared by hot pressing followed by die-upsetting processes with the above similar way were explored in this study. Three kinds of alloy powders, 2 wt.% Nd70Cu30, 2 wt.%Dy70Cu30 and 2 wt.% (Nd0.5Dy0.5)70Cu30, mixed with the commercial nanocomposite powder MQU-F were adopted for experiment, respectively. The as-mixed powders were hot pressed to fully density disc shape, and then hot deformed with 70% reduction ratio in thickness. In addition, the post-annealing at 600 oC was also adopted to modify the microstructures and magnetic properties. The coercivity of each sample doped with different alloy powders was shown in Fig. 1. For Dy70Cu30 (Mp=796 oC)-doped magnets, the coercivity increases from 15 kOe to 19.4 kOe. Similarly, for (Nd0.5Dy0.5)70Cu30

(Mp=608 oC)-doped magnet, the coercivity could also enhance from 15 kOe to 19.5 kOe. Comparing with Dy70Cu30-doped magnet, (Nd0.5Dy0.5)70Cu30-doped magnet shows an almost identical enhancement of coercivity of about 4 kOe. Quite importantly, it shows a beneficial effect of reducing the usage of Dy from 1.6 wt.% to 0.8 wt.%. Doping low melting point and Dy-less (Nd0.5Dy0.5)70Cu30 powders into commercial MQU-F powders for making high coercivity hot deformation NdFeB magnets might be a potential and economic way for mass production, details will be presented.

Fig.1 Coercivity of the magnets doped with different alloy powders. [1]X. Tang, R. Chen, W. Yin, J. Wang, X. Tang, D. Lee, et al., Applied Physics Letters, vol. 102, p.

072409, 2013.

B-203

PL-06

First Principle Calculation of Rare-Earth Dopant Partition and Magnetic Properties of RF3-doped

Nd-Fe-B Die-Upset Magnet

K. M. Kim(a), J. Y. Kim(a), H. W. Kwon(a), Imran Khan(a), J. S, Hong(a), J. G. Lee(b) and J. H. Yu(b),

(a) Pukyong National University, Busan, Republic of Korea 48547

(b) Korea Institute of Materials Science, Changwon, Republic of Korea 51508

Doping of rare earth atoms using fluoride (RF3) has been used as an effective means of enhancing coercivity of die-upset Nd-Fe-B-type magnet. Melt-spun Nd-Fe-B flakes are mixed with RF3 and then hot-pressed and die-upset. During the hot-pressing and die-upsetting, the rare earth dopant from doped RF3 substitutes some of Nd in either Nd2Fe14B matrix grain and/or Nd-rich grain boundary phase in the flake, thus enhancing coercivity. In this article, partitioning of the rare earth dopant in the Nd-Fe-B-type die-upset magnets doped with various RF3 was studied by the first principle calculation, and the calculation results were correlated with experimental results. Effect of the RF3–doping on the magnetic properties was investigated. Commercial melt-spun flakes (MQU-F : Nd13.6Fe73.6Co6.6Ga0.6B5.6) were mixed with RF3 (R = La, Ce, Pr, Nd, Dy). The mixture was hot-pressed and then die-upset. Partitioning of the rare earth dopant was examined by SEM equipped with EDX. The first principle calculation suggested that substitution of Nd in Nd2Fe14B matrix grain by the rare earth dopant depended upon type of the dopant atom. The calculation was verified by elemental mapping images of rare earth dopants. Substitution of some Nd in the Nd2Fe14B matrix grain by the rare earth dopant occurred actively in the die-upset magnets doped with RF3 (R = Ce, Pr, Nd, Dy). However, the substitution in the die-upset magnets doped with LaF3 took place less actively (Fig. 1(a), (b)). RF3 (R = Pr, Nd, Dy)-doping led to coercivity enhancement, and the most profound coercivity enhancement was achieved in the DyF3-doped magnet (Fig. 1(c)). Coercivity enhancement by the RF3 (R = Dy, Pr, Nd)-doping was attributed largely to the enhanced anisotropy field of the (Nd,R)2Fe14B-type grains (for DyF3-, PrF3-doping) and grain boundary restructuring (for NdF3-doping) in the surface shell of each flake. Fig. 1. (a) BSE and elemental mapping of the Nd13.6Fe73.6Co6.6Ga0.6B5.6 die-upset magnet doped with RF3 (R = Dy, Pr, Nd, Ce, La). (b) BSE images of Nd12.5Fe80.6B6.4Ga0.3Nb0.2 strip cast flakes coated with RF3 and diffusion-annealed at 800 C for 24 hrs. (c) Demagnetization curves of the Nd13.6Fe73.6Co6.6Ga0.6B5.6 die-upset magnet doped with RF3 (R = Dy, Pr, Nd, Ce, La).

B-204

PL-07

Improvement of magnetic properties in microfabricated

FePt/ Fe nano-composites upon post-annealing

R. Kurosu, H. Iwama, A. Sugawara, M. Doi, T. Shima

Faculty of Engineering, Tohoku Gakuin University, Tagajo, Japan e-mail: s1594351@g.tohoku-gakuin.ac.jp

The demand of renewable and sustainable energy drives us to develop high efficient electromagnetic conversion system. In particular, to open up a next generation motorization, the development of high performance motors consisting of rare-earth permanent magnets are strongly needed to fulfill the automotive applications such as hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs) and electric vehicles (EVs). However, due to an environmental and geometrical issues, the reduction of indispensable elements from the Nd-Fe-B sintered magnets and consequently, high performance new permanent magnets are required [1][2][3]. In this work, in order to confirm the effect of nano-composite structure and to find the optimum configuration, ring-shaped samples embedded with another magnetic materials have been investigated. L10 ordered FePt phase and bcc-Fe phase are selected as “hard” and “soft” magnetic phase, respectively. The samples were prepared by using an ultra-high vacuum magnetron sputtering system. A Fe seed layer of 1 nm and epitaxial Au buffer layer of 40 nm were grown on a MgO (100) single crystal substrate at room temperature (R.T.). The FePt layer with the thickness of 10 nm was deposited at a substrate temperature (Ts) of 225 ˚C. Then, the sample was annealed at Ta = 475 C for 1 hour. The ring shaped FePt arrays with 1.0 µm in outer diameter were microfabricated by using an electron beam lithography followed by an Ar ion milling. Then, soft magnetic Fe was deposited and embedded into the FePt rings. It is confirmed that well-defined shape of the FePt rings embedded with Fe have been successfully prepared by a multiple microfabrication process as shown in Fig. 1. The coercivity of the FePt/ Fe samples with inner diameter of 0.6 µm was increased from 5.1 kOe to 14.0 kOe after post-annealing at 500 C for 1 hour. [1] R. Skomski, P. Manchanda, P. Kumar, B. Balamurugan, A. Kashyap, D. J. Sellmyer. IEEE Trans. Mag, 49. 7 (2013). [2] J. S. Jiang. S. D. Bader. J. Phys.: Condens. Matter, 26. 9 (2014). [3] R. Skomski and J. M. D. Coey. Phys. Rev. B., 48. 15812 (1993).

Fig. 1 SEM image for FePt ring shaped embedded with Fe. The outer and inner diameters are 1.0 and 0.6 µm, respectively

B-205

PL-08

Effect of heat treatment on magnetic and electrical properties in Fe/Al2O3 core/shell nanocomposites

S. Y. Tong, M. J. Tung, W. S. Ko and Y. P.Wang Material and Chemical Research Laboratories, Industrial Technology Research Institute, Taiwan

e-mail: SYTong@itri.org.tw

With the development of the portable electronics devices, all electrical components, such as power chokes, are integrated with miniaturization. Magnetic-energy storaged materials play an important role in power chokes for DC/DC converters applications. Presently, NiZn-based ferrites are often used in power chokes, but the saturation magnetization Ms~60emu/g is lower due to the intrinsic structure limitations. In order to replace the ferrites for high power application, the iron-based magnetic alloy with highly Ms~180emu/g are good candidates. However, the commercial magnetic alloys are micron-sized in 20-50um with the lower electrical insulations(<10-2Ω-cm) and will induce the high eddy-current loss. In this research, we develop a method to fabricate the sub micron-sized (<1um) core/ shell nanocomposites. The normal Fe2O3 oxides are used as a starting powders and chemically precipitate the Al(OH)3 hydroxides on the surface. These as-prepared composite are treated at 800oC for few hours in a reduced Ar/H2 atmospheres and successfully transform to the Fe/Al2O3 nanocomposites. Fig show the dependences of magnetic and electrical properties on the different Al/Fe ratio. The experimental results shows the optimal Ms value~161 emu/g and electrical resistivity of 2.6×103Ω-cm in a Al/Fe ratio of 24%. In additions, the crystallization, surface morphology and high-frequency properties are also investigated. In summary, the hydrogen reduced treatment acts as an efficient method to prepare the metal core/insuation shell nanocomposites from oxides systems.

Fig：the dependences of magnetic and electrical properties on the different Al/Fe ratio. [1] I. Fergena, K. Seemanna, A.v.d. Wetha, A. Sch.uppenb, J. Magn.Magn.Mater.

242-245,146 (2002)

[2] P. C. Chiu, Y. Ku, Y. L. Wu, H. C. Wu, Y. L. Kuo, Y. H. Tseng, Aerosol and Air Quality Research, 14, 98( 2014)

B-206

EA-01

Scanning Tunneling Microscopy Study on Spintronic

Emergent Materials

Minn-Tsong Lin(a,b)

(a)Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (b)Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei,

Taiwan e-mail: mtlin@phys.ntu.edu.tw

We present here the study of scanning tunneling microscopy (STM) on emergent

materials with spin characteristics. Scanning tunneling spectroscopy (STS) is used to monitor the local electronic structure in nanometer scale for material surface, and further with help of a magnetic tip, can be spin-sensitive, becoming spin-polarized STM. Several examples will be given in this talk. The first one is the 2-D network of Fe-PTCDA (perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride) grown on Au(111) [1]. In this case, the STS study indicates that the frontier orbital shifts of the PTCDA molecules are correlated with the metal-organic coordination number, which affects the magnitude of charge transfer onto each PTCDA in the Fe-PTCDA hybridization system. SP-STM also provides the spin-response of the organic molecules when they are deposited on magnetic Co islands. [1,2] Another system is Rashba semiconductor BiTeI [3] with strong spin-orbit coupling, which is of great interest for use in spintronic devices exploiting the Rashba effect. Using spatially resolved tunneling spectroscopy across the lateral boundary between the two terminations, a previously speculated p-n junction-like discontinuity in electronic structure at the lateral boundary is confirmed experimentally. These findings realize an important step towards the exploitation of the unique behavior of the Rashba semiconductor BiTeI for new device concepts in spintronics. Another interesting finding in topological insulator (TI) system will be also discussed. Formation of Fe-PTCDA hybrids on the Bi2Se3 surface can reveal the functionality of PTCDA to prevent dopant disturbances in the topological surface state, providing an effective alternative for interface designs of realistic TI devices. [4] [1] H. H. Yang, Minn-Tsong Lin et al., ACS Nano 7, 2814-2819 (2013). [2]Y. H. Chu, Minn-Tsong Lin et al., ACS Nano 9, 7027-7032 (2015) [3] Christopher J. Butler, Minn-Tsong Lin et al., Nat. Commun. 5:4066 doi: 10.1038/ncomms5066 (2014). [4] H. H. Yang, Minn-Tsong Lin et al., Nano Letters 15, 6896-6900 (2015)

B-207

EA-02

The chiral symmetry in spin Hall effect

G. Chern

Physics Department and SPIN Center, National Chung Cheng University

Chiayi, Taiwan

The current induced magnetization switching driven by spin Hall effect in a

ferromagnetic/nonmagnetic (FM/NM) bilayered structure has chiral characteristic with

respect to both current density and external field. The origin of the chirality is due to

the cross product nature of the spin orbit coupling. Either clockwise or

counterclockwise characteristic may be defied according to the direction of the current

and external field. In this report we will show the relation between interface and the

chiral symmetry. By introducing a top structure (MgO/CoFeB/cap layer) and a bottom

structure (seed/CoFeB/MgO) we may obtain either a left hand or right hand mirror

symmetrical dependence on the spin Hall effect. Further, we introduce a symmetrical

structure of FM/NM/FM and show that the mirror symmetry may be disappeared in an

ideal condition. In the real system, we discuss how the symmetry affects both the Hall

resistance and magnetoresistance of the symmetrical trilayered structure.

B-208

EA-03

Magnetism, gate tunable transport and magneto-transport in (Cr,Sb):Bi2Se3 epitaxial films on

amorphous SiO2/Si

Jung-Chun-Andrew Huang

Physics Department, National Cheng Kung University, Taiwan

A topological insulator (TI) is an exotic material that has a bulk insulating gap and

metallic surface states with unique spin-momentum locking characteristics. Despite its

various important applications, large scale integration of TI

into MOSFET technologies and its coherent transport study are still rarely explored.

Here, we report the growth of high quality Cr and Sb coped Bi2Se3 thin films

on amorphous SiO2/Si substrate using MBE. Magnetism and gap opening can be

tuned by Cr concentration. By controlling the Sb concentration, Fermi level can be

tuned to stay below the conduction band. Large electrostatic field effect and

gate-tunable weak antilocalization (WAL) can be obtained at relatively low back gate

voltage for the (Cr,Sb):Bi2Se3 films. Our findings may pave the ways towards the

development of TI-based MOSFET and are promising for the applications of

electric-field controlled spintronic devices.

B-209

EA-04

Visualizing Spin-Dependent Molecule Symmetry at an Organic-Ferromagnetic Spinterface

Yu-Hsun Chu(a), Chuang-Han Hsu(a), (b), Chun-I Lu(a), Hung-Hsiang Yang(a), Tsung-Han Yang(a), Chi-Hung Luo(a), Kai-Jheng Yang(a), Shih-Hao Hsu(a),

Germar Hoffmann(a), (c), Chao-Cheng Kaun(b), (c), and Minn-Tsong Lin(a), (d), (e) *

(a)Department of Physics, National Taiwan University, Taipei, Taiwan

(b) Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan (c) Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

(d) Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan (e) Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

*e-mail: mtlin@phys.ntu.edu.tw

As promising building blocks in spintronics, organic molecules have shown a variety of advantages including long spin coherence time and length as well as superparamagnetism. In addition, contacting with ferromagnetic (FM) materials, molecules induce so-called “spinterfaces” at the organic-FM boundaries, at which new spin-polarized states appear and change the magnetic properties in these hybrid systems. While the spinterface may influence performance in spinctronic devices, it may also extend the possibility of organic spintronics. To conduct an investigation into spinterfaces, we visualized the spin-distribution within single pentacene (PEN, C22H14) on FM Co nanoislands on Cu(111) via spin-polarized scanning tunnelling microscopy (SP-STM) [1]. Near the Fermi level, the widely-used semiconducting PEN molecules show not only spin-polarization opposite to the Co substrate, but also spin-dependent symmetries. Combined with first-principles calculations, the experimental findings agree with the pz-d hybridization model, in which spin-dependent bonding types can result in different molecule symmetries. Our observations exhibit locally-reversed spin-polarization after molecule deposition, and reveal a concise way to predict molecular spin-distribution for π-conjugated molecules such as PEN in organic-FM hybrid structures.

[1] Y.-H. Chu, C.-H. Hsun, C.-I Lu, H.-H. Yang, T.-H. Yang, C.-H. Luo, K.-J. Yang,

S.-H. Hsu, G. Hoffmann, C.-C. Kaun, and M.-T. Lin, ACS Nano, 9, 7027-7032, (2015).

B-210

EA-05

A novel flexible magnetoelectric self-assembled BiFeO3-CoFe2O4 nanocomposite via van der Waal

heteroepitaxy

Tahta Amrillah(a), Yugandar Bitla(b), Kwangwoo Shin(c), Ying-Hui Hsieh(b), Liu-Heng Jui(b, Chih-Kuo Wang(b), Do Thi Hien(b), Ha Thai Duy(a), Yi-Ying Chin(4), Hong-Ji Lin(d), Kee Hoon Kim(c), Jenh-Yih Juang(a)*, and Ying-Hao

Chu(a), (b)*

(a)Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan

(b)Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

(c)CeNSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea

(d)National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan jyjuang@cc.nctu.edu.tw and yhc@nctu.edu.tw

Self assembled magnetic and multiferroic nanocomposites thin film have been a

topic of intense research for their profound potential applications. In addition to

growing high-quality phase separated heteroepitaxial nanocomposite, the strain

engineering that is conducive to enhance the tunability of material properties in general

and the magnetoelectric properties, in particular, is of the utmost importance in

exploring new possibilities. However, one of the major obstacles encountered by this

kind of approach is the clamping effect attributed from the rigid substrate. To this

respect, growing such heterostructures via the van der Waal epitaxial growth on mica

substrate is a natural alternative for circumventing this problem. In this study, we

investigated the magnetoelectric coupling between multiferroic (anti-ferromagnetic

and ferroelectric) BiFeO3 (BFO) and ferrimagnetic (magnetostrictive) CoFe2O4 (CFO)

in self-assembled vertically aligned nanocomposites grown on flexible MICA substrate.

We found that the BFO appears as nanopillars embedded in the CFO matrix with much

reduced substrate clamping effect, both BFO and CFO grow incoherently on mica.

Moreover, the magnetic and electric properties measurement evidently highlight the

enhanced magnetoelectric coupling between BFO-CFO grown on MICA. Therefore,

this study demonstrates a platform for fabricating highly flexible functional ME

sensors, which are robust against extreme conditions (thermal, mechanical and

chemical) with optimized performance.

B-211

EA-06

Magnetization Reversal of Nickel Three-Dimensional Antidot Arrays

Le Yu(a),(d), Bingqing Li(a), Xuzhao Chai(a),(d), Han-chang Yang(a), Sina Moeendarbari(b), Yaowu Hao(b), Di Zhang(c), Gang Feng(c), Ping Han(d),

Dustin A. Gilbert(e), Kai Liu(e), X. M. Cheng(a)

(a)Department of Physics, Bryn Mawr College, Bryn Mawr, PA 19010, USA (b)Department of Materials Science and Engineering, University of Texas at

Arlington, Arlington, TX 76010, USA (c)Department of Mechanical Engineering, Villanova University, Villanova, PA

19085, USA (d)School of Electronic Science and Engineering, Nanjing University, Nanjing

210093, China (e)Physics Department, University of California, Davis, CA 95616, USA

e-mail: xcheng@brynmawr.edu

Three-dimensional antidot arrays (3DAAs) have attracted considerable attention due to potential applications in photonic materials, sensitive sensors and high-capacity electrode materials. The periodic structure and high surface-to-volume ratio of magnetic 3DAAs provide an ideal system for studying the effect of the dimensionality and morphology on magnetic properties. Most of the work has focused on the dependence of coercivity on the dimensions in magnetic 3DAAs so far. In this work, we report our study of magnetization reversal in Ni 3DAAs by the first-order reversal curve (FORC) method [1] and micromagnetic simulations.

Ni 3DAAs were fabricated by electrochemical deposition into colloidal crystal templates of self-assembled polystyrene spheres. The samples have the same pore size of about 500nm but different thicknesses, ranging from 0.2 µm (half layer) to 1.5 µm (3.5 layers), confirmed by scanning electron microscopy (SEM). First order reversal curves of the samples were measured by a vibrating sample magnetometer. The FORC diagrams show a decrease in the weight of the irreversible feature, a decrease in the bias distribution and the development of a 90° symmetry in H/HR coordinates with the increasing number of layers. This FORC distribution fingerprints the increasingly interconnected network realized by the additional layers and the enhanced domain growth behavior.

Micromagnetic simulations using object oriented micromagnetic framework (OOMMF) reveal two major magnetization reversal mechanisms: (1) domain expansion in the large connected regions and (2) vortex formation, propagation and annihilation in the interstitial regions surrounded by the spherical voids. The irreversible peak in the FORC diagrams is mainly due to the domain expansion.

Work at Bryn Mawr College is supported by the National Science Foundation under Grant No. 1207085. Work at UCD supported by DMR-1008791 and DMR-1543582.

[1] D. A. Gilbert, et al., Scientific Reports, 4, 4204 (2014).

B-212

EA-07

Influences of magnetic anisotropy for Ni/(√3×√3)-Ag/Si(111) by silver capping layers

Yu-Ting Chow, Bin-Han Jiang, and Jyh-Shen Tsay*

Department of physics, National Taiwan Normal University, Taipei116, Taiwan *Email: jstsay@phy.ntnu.edu.tw

Because of the promising applications of new possible functionalities in

semiconductor technology, metal-semiconductor interfaces have attracted

considerable attention. Combined Auger electron spectroscopy and surface

magneto-optic Kerr effect are employed to study influences of silver overlayers on

Ni/√3×√3R30°- Ag/Si(111). The hysteresis loops for (a) as-deposited and (b) annealed

15 monolayer Ni/√3×√3R30°-Ag/Si(111) with and without Ag capping layers are

shown in Figure 1. As compared to the as-deposited Ni/√3×√3R30°- Ag/Si(111),

ultrathin silver of only 0.6 monolayer on annealed Ni/√3×√3R30°-Ag/Si(111) shows a

significant enhancement of the coercive force. This could be explained by the

smoothening of the top surface causing that the interfacial magnetic anisotropy of the

Ag/Ni interface is more dominant. This inference is consistent with the calculations of

increases (0.208 kJ/m3) of the effective magnetic anisotropy for

Ni/√3×√3R30°-Ag/Si(111) with and without Ag capping layers.

0.6 ML Ag

0 ML Ag

Figure 1. The hysteresis loops for (a) as-deposited and (b) annealed 15 ML

Ni/√3×√3R30°-Ag/Si(111) with and without Ag capping layers.

-400 -200 0 200 4000.000

0.001

0.002

0.003no anneal treatment

Magnetic field (Oe)

Ker

r si

gnal

s (a

rb. u

nits

)

-400 -200 0 200 400

anneal to 475 K first

Magnetic field (Oe)

B-213

EA-08

Structural and magnetic characterization of NiO/Co90Fe10 bilayers

Yu-Chi Chang(a), Ko-Wei Lin(a), Johan van Lierop(b)

(a) Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan

(b) Department of Physics and Astronomy, University of Manitoba, Winnipeg, R3T 2N2, Canada

e-mail: d103066001@mail.nchu.edu.tw

The exchange bias effect [1] results to the exchange coupling between a ferromagnetic (FM) material and an antiferromagnetic (AF) or ferrimagnetic material. In this work, we investigate the effects of post deposition magnetic field annealing on modifying the exchange coupling magnetism of NiO (~ 30 nm)/Co90Fe10 (~ 20 nm) bilayers prepared using a dual-ion beam sputtering deposition technique [2]. X-ray diffraction and transmission electron microscopy identified fcc NiO for the top layer and hcp Co90Fe10 (at%) for the bottom layer, in agreement with the deposition conditions. The NiO/Co90Fe10 bilayer exhibited soft magnetism with a low room temperature coercivity, Hc ~ 10 Oe, as characterized by VSM. The post deposition magnetic field annealing processes (under vacuum, using different applied fields, Happ, from 1-3 kG and temperatures up to 400 °C) were carried out in order to set the exchange bias coupling between the AF NiO and FM Co90Fe10. Results have shown that the NiO/Co90Fe10 bilayer exhibited similar soft magnetic properties using Happ.= 3 kG at 300 °C for 1 hour. However, with an increase of the annealing temperature to 400 °C, an enhanced Hc ~ 550 Oe with no observed loop shift was measured at room temperature. Our results indicate that the magnetization reversal mechanisms were affected strongly by exchange coupling between the Co90Fe10 and NiO layers, through modified spin structures between the AF and FM that are aligned during the field annealing processes. [1] J. Nogués, J. Sort, V. Langlais, V. Skumryev, S. Suriñach, J.S. Muñoz, M.D. Baró, Physics Reports, 422, 65 (2005). [2] K.-W. Lin, M. Mirza, C. Shueh, H.-R. Huang, H.-F. Hsu, and J. van Lierop, Applied Physics Letters, 100, 122409 (2012).

B-214

EA-09

The contribution of thermal Hall effect in anomalous Nernst and spin Seebeck effects

Yi-Jia Chen and Ssu-Yen Huang

Department of Physics, National Taiwan University, Taipei, Taiwan e-mail: b00202073@ntu. edu.tw

The anomalous Nernst effect (ANE) and the spin-Seebeck effect (SSE) are two of the

most important mechanisms to manipulate spin-polarized current and pure spin current

in spin caloritronics. While the ANE in ferromagnetic metals and the SSE in the

magnetic insulators have been extensively studied, the recent theoretical work [1]

shows that the thermal Hall effect, including the magnon Hall effect and the anomalous

Righi-Leduc effect, may have been overlooked in spin caloritronics. Most strikingly,

the thermal Hall effect with the anisotropic transverse temperature gradient has the

exactly same magnetic-field angular dependence with the ANE and SSE in

ferromagnetic metals and insulators. The thermal Hall effect alone could be used to

describe the observed spin-dependent signals. Therefore, it is very important to

investigate the contribution of the thermal Hall effect in both effects. By using different

Seebeck coefficients between devices and contact electrodes, in this work, we

systematically compare the magnitude of the thermal Hall effect with that of the ANE

in ferromagnetic metal Py and that of the SSE in magnetic insulator YIG. Our results

indicate that the contribution of the thermal Hall effect by thermal couple effect in the

ANE of Py and the SSE of YIG is negligibly small. The spin polarized current in ANE

and the pure spin current in SSE are the main mechanisms to manipulate thermal spin

current. [1] J.-E. Wegrowe, and H.-J. Drouhin, PHYSICAL REVIEW B 89, 094409, (2014)

B-215

EB-01

Role of spin on future biomedical science: Logical manipulation of living cells for novel cells-on-chip

Byungwha Lim, Sri Ramulu Torati, Xing Hao Hu, Sandhya Rani Goudu, CheolGi Kim*

Department of Emerging Materials Science, DGIST, Daegu, 42988, Republic of

Korea E-mail: cgkim@dgist.ac.kr

The manipulation ability of individual cells has significant applications for gene

sequencing, protein and bio-content analysis in single cell level for their heterogeneity

related with drug resistance aiming to lab-on-organ and new drug development. Even

though, various single cell platforms are exit, it is still challenge and complex to collect

rare cells and their digital manipulation in large-scale operation. In recent years the

flexibility of magnetic transport technology using nano/micro scale magnets for the

digital magnetophoresis has experienced tremendous advances and has been used for a

wide variety of single cells manipulation tasks such as selection, capture, transport,

encapsulation, transfection, or lysing of magnetically labeled and un-labeled cells. The

magnetic transport technology, which can be integrated within microfluidic channels,

relies on both magnetic energy and force tunability and remote control implemented by

micro-and nano-patterned magnetic structures. Here, we demonstrate a class of

integrated magnetic track circuits for executing sequential and parallel, timed

operations on an ensemble of single particles and cells. The magnetic circuitry tracks

are designed by conventional lift-off technology and were used for the passive control

of cells/particles similar concept to electrical conductor, diodes and capacitor. When

the magnetic tracks are combined into arrays and driven by rotating magnetic field, the

single cells are precisely control for multiplexed analysis. In addition, the concentric

cell translocation and separation were performed by the assembly of this magnetic

track into a novel architecture, resembled with spider web network, where all the cells

are concentrated into one position and then transported to apartments array for the

single cell analysis.

[1] B. Lim, V. Reddy, X. H. Hu, K. W. Kim, M. Jadhav, R. Abedini-Nassab, Y. W.

Noh, Y. T. Lim, B. B. Yellen; C. G. Kim, Nat. Commun. 2014, 5, 1

[2] S. Anandakumar, V. Sudha Rani, S. Oh, B. L. Sinha, M. Takahashi, C. G. Kim, Bi

osens Bioelectron. 2010, 26, 1755.

B-216

EB-02

Static and dynamic magnetic properties of intercellular magnetic nanoparticles for biomedical applications

Yasushi Takemura

Electrical and Computer Engineering, Yokohama National University, Japan

e-mail: takemura@ynu.ac.jp

Magnetic nanoparticles (MNPs) are used or expected to be used for various biomedical applications such as contrast agents for magnetic resonance imaging (MRI), carriers of drug delivery system (DDS), heating agents for magnetic hyperthermia and tracers for magnetic particles imaging (MPI). Dynamic magnetization properties of the MNPs are significant especially for the applications of hyperthermia and MPI. In this talk, evaluation of magnetic properties, especially magnetic relaxation of intercellular magnetic nanoparticles is discussed.

The temperature rise of the MNPs is essential for hyperthermia. It is measured in order to evaluate their specific loss power (SLP) or specific absorption rate (SAR). But this calorimetric measurement has some ambiguity and limitation depending on samples and other conditions. We measured dynamic hysteresis curves of the MNPs and reported that the area of hysteresis curves agreed well with the calculated SLP. The field and frequency dependences of magnetic loss was analyzed by the dynamic hysteresis measurements [1]. Recently the SLP of intercellular MNPs has successfully measured (Fig. 1 and 2) [2]. We could also clarify contributions of Brownian and Néel relaxations to relaxation process of the MNPs, which is significant for the application of MPI as well as hyperthermia application. [1] S. Ota, T. Yamada, Y. Takemura, J. Appl. Phys. 117, 17D713, 2015. [2] S. Ota, T. Yamada, Y. Takemura, J. Nanomaterials, 2015, 836761, 2015.

0

10

20

30

40

50

60

0 100 200 300 400 500 600

LiquidFixedCellular

SL

P [k

W/k

g-F

e]

Frequency [kHz]

8 kA/m

Fig. 1. Microscopic and schematic images of intercellular magnetic nanoparticles. [2]

Fig. 2 The dependence of SLP on excitation frequency. [2]

B-217

EB-03

Magnetic Micro-shuttles: Bioengineering at the cellular level

R. Sooryakumar

Department of Physics, The Ohio State University.

soory@physics.osu.edu

One of the major challenges in nanoscience, and the advancement of

nanotechnology in general, is the development of precision tools for the capture,

manipulation and transport of biological entities with directed forces. The difficulty of

such tasks becomes even more pronounced in a native fluid environments when

stochastic Brownian motion disrupts targeted activities.

We have developed new approaches based on reprogrammable magnetic signatures

patterned on a surface, to create remotely-controllable microscopic magnetic shuttles.

Requiring only five tiny electromagnets, a game controller and the power equivalent to

a 60W light bulb, tunable femto- to pico-Newton range forces guide, assemble and

manipulate biological cells and micro-organisms in a fluid.

The principles underlying these joystick- and voice-activated approaches, that have

been successfully implemented for fundamental nanoscience, bioengineering and

medicine, will be discussed as we move towards realizing new intra-cellular probes

within living cells.

B-218

EB-04

Development and application of spintronic sensors in smart and sustainable living

Philip W. T. Pong, Y. Du, K. Zhu, X. Liu

Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong

e-mail: ppong@eee.hku.hk

Spintronic sensors can find emerging applications beyond information storage and

enable smart and sustainable living. Healthy and sustainable living style is the

ambition in the 21st century, and advanced sensing techniques are its critical enabler.

New sensing platforms combining spintronic sensors and magnetic materials can

realize unprecedented detection in healthcare and power system to ensure holistic

wellness and constant and reliable supply of electricity for our living. In this paper we

discuss the development of spintronic sensors and their applications complemented by

magnetic materials in healthcare and power grid in connection with smart and

sustainable living. For example, we will explore their possible applications in realizing

point-of-care diagnostic devices for early cancer detection and monitoring power

transmission systems to enable smart grid, which are evidenced by our initial research

achievements. The future contribution of spintronic sensors towards the essential

elements of smart and sustainable living can be foreseen.

B-219

EB-05

Preparation of magnetic iron oxide nanostructures and

their applications

Jun DING

Department of Materials Science & Engineering, National University of Singapore,

Singapore 119260

Magnetic nanoparticles under radio-frequency magnetic field can generate a considerable heat,

which can be used for cancer treatment – magnetic hyperthermia. Cancer cells can be killed if the

local temperature raises over 42 C, while normal cell may survive up to 45 C. Many works have

demonstrated the good hyperthermia performance against cancer after intratumoral injection.

However, the more ideal delivery path is the intravenous injection. But, there are still technical

challenges for practical applications, such as effective delivery with a substantial quantity in tumor

and accurate in-vivo estimation of its concentration. In this work, we have prepared ultrafine

Gd-doped Fe3O4 nanoparticles with a particle size of 4-5 nm. After suitable surface

functionalization, these nanoparticles have excellent colloidal stability. The presence of Gd enables

us to estimate the distribution of these Gd-doped nanoparticles accurately after intravenous injection.

Long blood circulation time has been obtained. Considerable amount of nanoparticles was found in

the implanted tumor. Using MRI technique, T1-weighted image can be used for monitoring of

distribution of magnetic nanoparticles. The MRI parameter R1 can be used for an accurate in-vivo

estimation of nanoparticle concentration in tumor. This work has shown the potential of Gd-doped

iron oxide nanoparticles for hyperthermia cancer treatment after intravenous injection.

B-220

EB-06

Spintronic linear motor for manipulation of magnetic beads

Xiaoxi Liu Spin Device Technology Center, Shinshu University

e-mail: liu@cs.shinshu-u. ac.jp

Microfluidic devices are key component of micro total analysis systems or Lab on Chip that are fundamental systems in bio researches. Detecting and manipulation of biomolecular can be achieved by different type of microfluidic systems. Here we will present our recent results to detect and manipulation of magnetic beads by spintronic approaches.

Magnetic thin films with perpendicular magnetic anisotropy field smaller than the demagneticzation field show typical stripe domain configuration. This is a unique domain configuration with magnetization mainly lying on the film plane but curing due to the perpendicular magnetic anisotropy. Such a domain configuration provide an ideal approach for microfluidic systems due to i) the stray field due to the weak perpendicular magnetic anisotropy can attach magnetic beads effectively; ii) only magnetic beads with suitable sizes can be attached because of the periodic domain configuration; iii) stripe domains can be easily moved by applying DC current or microwaves due to the spin transfer torque. It is an ideal spintronic linear motor for manipulation of magnetic beads for bio applications.

In this experiment, for the first time, by introducing both perpendicular and transverse magnetic anisotropy, we successfully achieved transverse stripe domain walls in microwires as shown in fig.1 The magnetic wires are prepared with conventional photolithography. Magnetic films were deposited by facing targets sputtering to introducing transverse magnetic anisotropy in the magnetic wires. Perpendicular magnetic anisotropy is controlled by additives of rare-earth elements. Such combination successfully controlled both direction and period of the stripe domains.

Both DC pulse and microwaves have been applied to drive the domains, and hence the attached magnetic beads. The efficiency of the spin transfer torque and the domain wall resonances will also be presented in detail.

Fig. 1. Magnetic force microscope image of a magnetic wire with wire width of 6 micrometer. Clearly transverse domains, with stray field period of around 1.5 micrometer, was found both on and near the wire.

B-221

EC-01

The quest for Magnetocaloric materials: Rare earth

intermetallics and Oxides

R. Nirmala Department of Physics

Indian Institute of Technology Madras

Chennai 600 036 INDIA

Magnetic refrigeration is considered as one of the potential alternative to the

conventional gas compression technology because of the expected energy efficiency

and ecofriendliness. Magnetic cooling is based on the intrinsic magnetic property of

materials to respond favourably upon the application/removal of external magnetic

field under adiabatic conditions with a change of temperature. In the ongoing quest for

magnetocaloric materials for various applications, several rare earth based

intermetallic compounds, transition metal alloys and oxides are characterized more

vigorously. A brief review of the topic will be presented along with some recent results

from the group on rare earth intermetallics and oxides that exhibit metamagnetic

transition.

B-222

EC-02

Electrical field control of large magnetization reversal in a helimagnets

Kee Hoon Kim

CeNSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea

(Tel: +82-2-880-9068, Fax: +82-2-888-0769, khkim@phya.snu.ac.kr) Despite its technical and fundamental importance, reversal of macroscopic magnetization by an electric field

(E) has rarely been achieved and remains a considerable challenge. Here, we report the strong modulation and large

reversal of magnetization (M) by E in a multiferroic Ba0.5Sr1.5Zn2(Fe0.92Al0.08)12O22 crystal at zero magnetic field,

in which a transverse conical spin state exhibits a remanent M and electric polarization below ~150 K. Upon sweeping E

through the range of ±2 MV m-1, M varied quasi-linearly in the range of ±2 μB per f.u., resulting in the reversal of M.

Moreover, the remanent M exhibited non-volatile changes of ±0.15 μB per f.u., depending on the history of the applied

electric fields. The strong modulation and non-volatile two-states of M at zero magnetic field were observable up to ~150

K. Nuclear magnetic resonance measurements provided microscopic evidence that the electric field and the magnetic field

play equivalent roles in modulating the volume of magnetic domains. Our results suggest that soft ferrimagnetism with

small magnetic anisotropy and the related transverse conical state are key ingredients to achieve the giant converse

magnetoelectric effect, indicating a novel pathway toward achieving large magnetization reversal by electric fields at

fairly high temperatures [1].

[1] Y. S. Chai et al., Nature comm. 5, 4208 (2014); The control of magnetization by an electric field remains as one of

great challenges in materials science. Multiferroics, in which magnetism and ferroelectricity coexist and couple to each

other, could be the most plausible candidate to realize this long-sought capability. While recent intensive research on the

multiferroics has made significant progress in the sensitive magnetoelectric (ME) effects, the electrical control of

magnetization, the converse effect, has been observed only in a limited range far below room temperature. Here I will

summarize recent developments on how the spiral magnets, particularly based on the hexagonal ferrites, can realize the

viable, converse ME effect in a broad temperature range including room temperature. Starting with the chemical aspect of

the hexaferrite materials, I discuss the importance of the strong magnetoelectric (ME) coupling to achieve the significant

converse ME effect. The three key material parameters, magnetic anisotropy, spin frustration, and spin exchange

interaction, will be pointed out. By controlling those key parameters, we demonstrate that the four state magnetization

curves can be obtained at room temperature by an electric field (Fig. 1). We also show based on the similar mechanism

that the magnetization reversal by an electric field can be realized with fast switching time.

Sae Hwan Chun et al., Phys. Rev. Lett. 108, 177201 (2012); ibid, 104, 037204 (2010); Y. S. Chai et al., (unpublished).

Figure 1. Control of M by E at zero H-bias at different magnetoelectric annealing conditions.

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EC-03

Conductance switching and tunneling characteristics of

remotely controlled magnetostriction-based

nanocontacts

S. Narayana Jammalamadaka(a)*, Sebastian Kuntz(b), Oliver Berg(b), Wolfram Kittler(b), U. Mohanan Kannan(a), J. Arout Chelvane(c), and

Christoph Sürgers(b)

(a)Magnetic Materials and Device Physics Laboratory, Department of Physics,

Indian Institute of Technology Hyderabad, Hyderabad 502285, India (b) Karlsruhe Institute of Technology,Physikalisches Institut,

Wolfgang Gaede Str. 1, Karlsruhe, 76131, Germany and (c)Defence Metallurgical Research Laboratory, Hyderabad 500058, India.

Email: surya@iith.ac.in

We demonstrate the utilization of the giant magnetostriction of Tb0.3Dy0.7Fe1.95

in a mechanically controlled break-junction device to control the conductance in a

remote way by variation of an applied magnetic field H at room temperature. The

Tb0.3Dy0.7Fe1.95 grain-oriented compound was obtained by employing a modified

Bridgman method. The rod was grown with a preferred crystallographic orientation

with <110> axes along the rod axis. Reproducible switching of the electrical

conductance was observed at room temperature with the externally applied magnetic

field perpendicularly to the wire long axis. Below 70 K, we observe a hysteresis for the

conductance switching which is attributed to the pinning of domain walls. The

switching of the conductance is distinctly different when the magnetic field is applied

in the parallel or perpendicular direction with respect to the long wire axis, which is

attributed to the different magnetic anisotropy in the two orientations. We also discuss

about the tunneling characteristics of the Tb0.3Dy0.7Fe1.95 nanocontacts at 10 K. These

results are important for developing a device based on a nano-electromechanical

system operating at room temperature.

Refereces:

1. S. Narayana Jammalamadaka, S. Kuntz, Oliver Berg, W. Kittler, U. M. Kannan,

J. Arout Chelvane, and C. Sürgers, Sci. Rep. 5, 13621 (2015).

B-224

EC-04

Engineering ferromagnetic lines in graphene by local oxidation and hydrogenation using AFM lithography

Bae Ho Park Department of Physics, Konkuk University, Seoul 143-701, Korea

Email:baehpark@konkuk.ac.kr

Monolayer graphene with sp2-carbon-atom network is a promising platform for

next-generation spintronic devices due to its high carrier mobility and long spin

relaxation length.

For implementation of practical and high-density graphene-based spintronic

devices, we need to define nanoscale areas with ferromagnetic properties on graphene.

Up to now, conventional ferromagnetic metal electrodes accompanied by barrier

insulators have been used for injection and detection of polarized spins in

graphene-based spintronic devices. If graphene-based materials show ferromagnetic

behaviors, they will become ideal candidates for spin injectors and detectors, because

they structurally, chemically, and electrically well matches graphene.

In this presentation, I will report on local magnetic characteristics of nanoscale

graphene oxidized and hydrogenated by atomic force microscope (AFM) lithography

without conventional sources of surface contamination and chemical agents. By using

AFM lithography, we can selectively control functional groups and their coverages on

the nanoscale at the surface of graphene. By performing magnetic force microscope

(MFM) measurement, we can clearly distinguish local magnetic signal of selectively

oxidized or hydrogenated graphene from that of surrounding pristine graphene which

does not produce ferromagnetic signal. The nanoscale oxidized and hydrogenated

graphene show experimental evidences for room-temperature ferromagnetism.

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EC-05

Epitaxial Cobalt Ferrite Thin Films on Muscovite for Flexible Electronics

Ying-Hao Chu(a) (b) (c) (a)Department of Materials Science and Engineering, National Chiao Tung University,

Hsinchu 30010, Taiwan (b)Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

(c)Department of Electrophysics, National Chiao Tung University, Hsinchu 30010,

Taiwan

Over the past decades, a quick rise of flexible devices revolutionizes the

electronics into a new era of applications, such as rollable display, bendable solar cells,

wearable electronic products, biotechnologies, etc. They gradually change personal

habits in daily life. In order to expand the practical applications of flexible electronics,

more functional materials are highly on demand. However, a generic approach to build

up flexible electronics based on magnetic oxides is yet to be developed. In the pursuit

of proper flexible substrates for the integration of future electronics, muscovite sheets,

a group of layered materials, has increasingly attracted attention because of its great

potential to overcome the technical difficulties found in polymer substrates. For

example, muscovite is flexible and transparent when thickness is below 100 um. In this

study, we take several a magnetic oxide as a model system to demonstrate a pathway to

fabricate magnetic oxides for transparent and flexible electronics. Spinel CoFe2O4 is

selected as a model system because it has superior magnetic properties with high Curie

temperature, large magnetocrystalline and magnetostrictive anisotropy. we have

fabricated a new magnetostrictive bimorph composed by a heteroepitaxy of the

CoFe2O4 thin film and the flexible muscovite. Unlike the conventional van der Waals

epitaxial films on muscovite, this system shows a layer-by-layer growth mode and

suffers a large tensile strain along out-of-plane direction, indicating a strong bonding

between the film and the substrate. Such a compact connection provides a wonderful

platform for operating the magnetostrictive material. Here we have successfully

demonstrated either the varied magnetic anisotropy by deforming the sample or the

controllable deformation of sample utilizing the magnetic force. This study highlights

the great potential of flexible magnetic films for futere soft technologies.

B-226

EC-06

Layered Structure of Magneto-Optical Kerr Rotation of

[(GeTe)2(Sb2Te3)1]n Superlattices

Do Bang(a,b,c), Hiroyuki Awano(a,b), Yuta Saito(c,d), Juni Tominaga(c,d)

(a) Toyota Technological Institute, Nagoya, Japan

(b) CREST, Japan Science and Technology Agency, Saitama, 332-0012, Japan (c) Institute of Materials Science, VAST, 18 Hoang Quoc Viet, Hanoi, Vietnam (d) Nanoelectronics Research Institute, National Institute of Advanced Industrial

Science & Technology (AIST), Tsukuba, Japan e-mail: dobang@toyota-ti.ac.jp

[(GeTe)2/(Sb2Te3)1]n topological superlattices based interfacial phase change memory (iPCM) has recently attracted attention because it processes both huge magnetoresistance (MR) and anomalous magneto-optical Kerr rotation (MOKR). It is expected that the MOKR of the high temperature phase (SET phase) would depend on the layered structure of [(GeTe)2/(Sb2Te3)1]n topological superlattices. In this study, we investigate and discuss the dependence of MOKR on the layered structures and the repetition number (n) of the superlattice.

To investigate the effect of layered structure on MOKR in the superlattice, [(GeTe)2(Sb2Te3)1]n films were fabricated by r.f. magnetron sputtering using two-inch composite targets (GeTe and Sb2Te3) with different GeTe thicknesses and the repetition number (n = 1 – 5) and a Si3N4(20 nm) cover layer. The Kerr rotation was measured by using a 690-nm wavelength linear polarized laser beam which incidents at an angle of 4 degrees from the normal to the sample surface. The films were set on a heater stage surrounded by a magnetic coil. The crystalline of the superlattices was investigated using X-ray Diffraction technique.

Similar to a previous report [1], the Kerr signal was within noise at room temperatures, while large MOKR peaks were observed at high temperature range (430 K). For wide magnetic field range from + 20 kOe to – 20 kOe, number of resonance peaks with a mirror-symmetry was changed with respect of the layered structures of the superllatices. We also found that the resonant field of each MOKR peak can be modulated by the repetition number (n) of the [(GeTe)2/(Sb2Te3)1]n superlattice. [1] 3. D. Bang, H. Awano, J. Tominaga, A. V. Kolobov, P. Fons, Y. Saito, K. Makino, T.

Nakano,M. Hase, Y. Takagaki, A. Giussani, R. Calarco and S. Murakami, Sci. Rep. 4,

(2014) 5727.

B-227

EC-07

Heteroepitaxial CoFe2O4/Muscovite Bimorph with Large Magnetostriction for Flexible Electronics

Chih-Kuo Wang(a), Heng-Jui Liu(a), Dong Su(b), Do Thi Hien(c), Ha Thai Duy(d), Kun-Hong Wu(e), Yi-Chun Chen(e), Jenh-Yih Juang(d), Qing He(f),

Shien-Uang Jen(c),(g), and Ying-Hao Chu(a), (c), (d)* (a)Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan

(b)Center for Functional Nanomaterials, Brookhaven National Laborator, NY 11973, United States (c)Institute of Physics, Academia Sinica, Taipei, Taiwan

(d)Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (e)Department of Physics, National Cheng Kung University, Tainan, Taiwan

(f)Department of Physics, Durham University, Durham DH1 3LE, United Kingdom (g)Institute of Optoelectronic Science, National Taiwan Ocean University, Keelung, Taiwan

e-mail: jlpsc120@gmail.com

In this study, spinel CoFe2O4 is adopted as a model system of flexible magnetostrictive devices (Fig. 1) owing to its superior magnetic properties with high Curie temperature [1], large magnetocrystalline and magnetostrictive anisotropy [2-5]. By PLD method, CFO film was established on layered and flexible muscovite substrates (Fig. 2). Reflection high energy electron diffraction, AFM, high-resolution x-ray diffraction and TEM were utilized to identify surface morphology, crystal structure and epitaxial relationships of CFO/MICA heteroepitaxial bimorph. In order to demonstrate this heteroepitaxial large magnetostrictive CFO/MICA bimorph, magnetic properties was also characterized via SQUID, XMCD and digital holographic microscopy technics. In this work, we have successfully demonstrated the varied magnetic anisotropy by deforming the sample as well as the controllable deformation of sample utilizing the magnetic force. This study highlights the great potential of flexible magnetic films for next-generation soft technologies.

[1] L. Bouet, P. Tailhades, A. Rousset, J. Magn. Magn. Mater. 153, 389-396 (1996).

[2] R. M. Bozorth, E. F. Tilden, A. J. Williams, Phys. Rev. 99, 1788-1798 (1955).s

[3] J. C. Slonczewski, Phys. Rev. 110, 1341-1348 (1958).

[4] Y. X. Zheng et al., J. Appl. Phys. 110, 043908 (2011).

[5] D. Fritsch, C. Ederer, Phys. Rev. B 82, 104117 (2010).

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PM-01

The Magnetic Properties of Transition-metal Atom Adsorbed Two Dimensional GaAs Nanosheet

Jia. Luo, Gang. Xiang,Tian Yu College of Physical Science and Technology, Sichuan University, Chengdu, 610064, China

e-mail: luojia1007@sina.com

By using first-principles calculations within the framework of density functional theory,[1] the magnetic properties of 3d transitional metal (TM) atoms (from Sc to Zn) adsorbed two dimensional (2D) GaAs nanosheets (GaAsNSs) are systematically investigated. The 2D GaAsNS is composed of 16 Ga and 16 As atoms, which are repeated along the x- and y-directions. 3d TM atoms adsorbed on hollow site (center of the hexagonal ring formed by 3 Ga and 3 As atoms).[2-3] Upon TM atom adsorption, GaAsNS, which is a nonmagnetic semiconductor, with an estimated gap of 1.29 eV[4] can be tuned into a magnetic semiconductor (Sc, V, and Fe adsorption), a half-metal (Mn adsorption), or a metal (Co and Cu adsorption). The magnetic moment of Sc, V, Fe and Mn adsorbed GaAsNS is 1 μB, 1 μB, 1 μB and 2 μB respectively. Our calculations show that the strong p-d hybridization between 3d orbit of TM atoms and 4p orbit of neighboring As atoms is responsible for the formation of chemical bonds and the origin of magnetism in the GaAsNSs with Sc, V and Fe adsorption. However, Mn 3d orbit with more unpaired electrons hybridizes with not only As 4p but also Ga 4p orbits, resulting in a stronger exchange interaction. Our results may be useful for electronic and magnetic applications of GaAsNS-based materials.

Fig.1. Bandstructure of Fe and Mn adsorbed GaAsNS

[1] Kresse G and Furthmüller J Phys. Rev. B 54 11169.(1996) [2] Sevinçli H, Topsakal M, Durgun E and Ciraci S Phys. Rev. B 77 195434.(2008) [3] Mao Y, Yuan J and Zhong J J. Phys.: Condens. Matter 20 115209.(2008) [4] Şahin H, Cahangirov S, Topsakal M, et al. Phys. Rev. B 80 155453.(2009)

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PM-02

Magnetic Properties of Weak Itinerant Electron Ferromagnet Au4V under high magnetic fields

K. Koyama(a), A. Tanaka(a), S. Yoshinaga(a), Y. Mitsui(a), H. Sasaki(b), T. Kanomata(c)

(a) Graduate School of Sci. & Eng., Kagoshima Univ., Kagoshima890-0065, Japan

(b)Faculty of Engineering, Tohoku-Gakuin University, Tagajyo 985-8537, Japan (c)Research Institute for Engineering and Technology, Tohoku Gakuin University,

Tagajo 985-8537, Japan e-mail: koyama@sci.kagoshima-u.ac.jp

Intermetallic compound Au4V with a Ni4Mo-type tetragonal is a weak itinerant

electron ferromagnet (WIEF) with a Curie temperature TC of 42 K [1, 2]. For WIEF,

Takahashi proposed a spin fluctuation theory, in which quantum spin fluctuations

(zero-point spin fluctuations) were considered [2, 3]. In this study, we performed

magnetization measurements of Au4V in

magnetic fields H up to 130 kOe in order to

estimate the characteristic parameters (T0 and

TA) of Takahashi’s spin fluctuation theory.

A polycrystalline sample of Au4V was

prepared by arc-melting a mixture of

stoichiometric mounts of pure elements (Au, 4N;

V, 4N) in an argon atmosphere. Magnetization M

measurements were carried out using a VSM for

0 ≤ H ≤ 130 kOe and 4 ≤ T ≤ 200 K.

Fig. 1 shows the isothermal M2 vs. H/M plot of

Au4V. The spontaneous magnetization (ps), T0

and TA were estimated to be 0.26 B/V, 1.28x103

K and 1.97x103 K, respectively, by the linear extrapolation to H/M = 0 for the M2 vs.

H/M plot. Obtained results show that the magnetism of Au4V is represented by

Takahashi’s spin fluctuation theory for WIEF.

[1] L. Creveling, Jr. and H.L. Luo, Phys. Rev. 176, 614 (1967). [2] Y. Takahashi, Spin Fluctuation Theory of Itinerant Electron Magnetism, Springer Tracts in Modern Physics vol. 253, (Berlin 2013). [3] Y. Takahashi, J. Phys.: Condens. Matter, 13, 6323 (2001)

Fig. 1. M2 vs. H/M plot of Au4V.

B-230

PM-03

Transmission Line Modelling of Strip-Mesh Screens Coated with Ferrite Sheet

Hyun Ho Park(a), Jong Hwa Kwon(b), Sang Il Kwak(b), Seungyoung Ahn(c)

(a)Department of Electronic Engineering, University of Suwon, Hwaseong, Korea (b) Electronics and Telecommunications Research Institute, Daejeon, Korea

(c)The Cho Chun Shik Graduate School for Green Transportation, KAIST, Daejeon, Korea

e-mail: hhpark@suwon.ac.kr

Modern mobile devices require electromagnetic shielding structures with light weight, physical flexibility, and even optical transparency. Wire-mesh screens have been considered as the best alternative electromagnetic shields satisfied these requirements. So far, considerable research has been conducted with respect to the electromagnetic properties of wire-meshes or perforated screens. In [1], the far-field shielding behavior of mesh-screens with square shape and small size in comparison to the wavelength was investigated by employing an equivalent sheet-impedance concept. Recently, the near-field shielding performance of the perforated screen in the presence of a high impedance dipole source was studied [2].

In this paper, a transmission line modeling method for shielding analysis of strip-mesh screen coated with a ferrite sheet is proposed. To estimate near-field shielding performance, an accurate wave impedance in the shielded region close to the strip-mesh screen is devised and employed in the transmission line model.

From the results, it has been found that the magnetic field shielding of the strip-mesh screen is much lower than the electric field shielding in the low frequency range. This is due to the fact that the shield impedance of the strip-mesh screen decreases as the frequency decreases. Empolying a ferrite sheet contributes to enhancement of the magnetic field shielding at the near-field shield region in the low frequency range.

To verify the proposed model, comparison of the electric and magnetic field shielding effectiveness was conducted by using numerical simulations. Good agreement between the transmission line model and numerical solution was achieved. In terms of the computation time, the proposed method is more effective than the numerical simulation for the shielding performance analysis of of strip-mesh screen coated with a ferrite sheet. [1] K. F. Casey, IEEE Transaction on Electromagnetic Compatibility, 30, 298 (1988). [2] R. Araneo, G. Lovat, S. Celozzi, IEEE Transaction on Electromagne- tic Compatibility, 53, 706 (2011).

Fig. 1 Geometry of problem.

B-231

PM-04

Effect of sintering temperature on electrical transport mechanism and thermal properties of Pr2/3Sr1/3MnO3

Ramesh Chandra Bhatt(a), Ashok Rao(b)*, Mamatha D Daivajna(b),V. P. S.

Awana(a), C. F. Lin(c), and Y. K. Kuo(c)

(a)Quantum Phenomena and Applications Division, National Physical Laboratory (CSIR), New Delhi-110012, India

(b)Department of Physics, Manipal Institute of Technology, Manipal University, Manipal-576104, India.

(c)Department of Physics, National Dong-Hwa University, Hualien 974, Taiwan

e-mails: ashokanu_rao@rediffmail.com; ykkuo@mail.ndhu.edu.tw

Electrical and thermal properties, including electrical resistivity, Seebeck coefficient,

thermal conductivity, and specific heat, of polycrystalline samples of Pr2/3Sr1/3MnO3

prepared at different temperatures (Ts) are reported. It is found that electrical and

thermal properties of the presently studied Pr2/3Sr1/3MnO3 samples strongly depend on

the sintering temperature. Electrical resistivity data (T) was analyzed using standard

models. It is revealed that electron-electron scattering processes play a major role in

the conduction process in the low-temperature regime. However, (T) follows the

small polaron hopping (SPH) model at high temperatures. Analyses of the Seebeck

coefficient data S(T) show that electron-magnon scattering dominates the

thermoelectric transport in the metallic region. On the other hand, high-T S(T) data can

be well described by the SPH model, consistent with the electrical resistivity results.

Thermal conductivity (T) is found to increase with increasing Ts, indicating a better

crystalline Pr2/3Sr1/3MnO3 samples can be obtained at a higher sintering temperature.

Specific heat CP(T) results show that the samples sintered at higher temperatures

exhibit a sharper transition around the Curie temperature TC and the entropy change

associated with the transition increases with increase in sintering temperature. These

observations suggest that the sintering temperature is an important parameter to choose

materials for application such as magnetic refrigerator in these manganite perovskites.

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PM-05

Frequency Dependence of Hysteresis Curves Based on Mean Field Model with Domain Structure

Takashi Shirane, Yuuichi Takahashi National Institute of Technology, Sendai College, Sendai, Japan

e-mail: shirane@sendai-nct.ac.jp

This paper presents a hysteresis model to express magnetization curves as a function of field frequency, field amplitude, and temperature near Curie point TC.

In previous work, a phenomenological model of hysteresis has been developed based on a mean field theory with a domain structure [1]. When magnetic field h is applied, the model generates quasistatic magnetization m curves on the both sides of TC. To date, the model has only dealt with time independent hysteresis. The equations can, however, be extended to account for time dependent effects. Fig 1 show typical hysteresis curves of M at temperatures below TC.

The frequency-dependent magnetization M(t) is obtained from the quasistatic magnetization M as a solution of following equation:

mtmdt

tdmΛ

dt

tmd

2

2

,

where n is the natural frequency, and is a damping factor of the domain-wall displacement [2]. Fig. 2 shows typical hysteresis curves of M(t) at temperatures below TC. Magnetization curves at various frequencies and at various temperatures near TC will be shown in the full paper. [1] T. Shirane, Material Research Innovations, 19, S3-1 (2015). [2] D. C. Jiles, IEEE Transaction on Magnetics, 29, 3490 (1993).

Fig. 1 The quasistatic magnetization

curves below TC.

Fig. 2 The time-dependent

magnetization curves below TC.

-0.001 0 0.001 0.002

-0.10

-0.05

0.00

0.05

0.10

h

K = 0.137c = 0.2 = 24

m

= -0.023

= -0.012

-0.001 0 0.001 0.002

-0.10

-0.05

0.00

0.05

0.10

h

K = 0.137c = 0.2 = 0

m

= -0.023

= -0.012

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PM-06

Study the Stability of 360-degree Transverse domain-wall in a magnetic wire

Yee-Mou Kao, Lung-Shiang Tsai, Deng-Shiang Shiu, Kuo-Chan Huang, Lance Horng

Department of Physics, National Changhua University of Education, Changhua,

Taiwan e-mail: ymkao@cc.ncue.edu.tw

Using the collective coordinates method(CCM), we analytically study how the

combination of two180-degree transverse domain walls(TDWs) become to one

360-degree transverse domain wall. The CCM was developed in the 1970s with the

aim of quantization of soliton systems in quantum field theory[1]. It is a

one-dimension-variational approximation method which is well done qualitatively in

the magnetic nanowire system. In this study, we want to explain why the combination

of two different chirality of 180-degree DWs will be annihilated or preserved leading

to the 360-degree DW. In the latter case, we investigated the distance and the stability

of the two 180-degree DWs and went on to analyse the affection of each force. These

results are consistent with former simulation [2]. This study hopes to assist the

understanding the mechanism of the magnetic DW storage devices.

[1] Rajaraman R 1982 Solitons and Instantons (Amsterdam: Elsevier)

[2] I. Purnama, C.S. Murapaka, W.S. Lew, and T. Ono, Appl. Phys. Lett. 104, 092414

(2014).

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PM-07

First-Principles Study of Electric Field Effects on Magnetic Anisotropy Energy in 2-Dimension VS2

Huei-ru Fuh(a), Ke-chuan Weng(b), Yeu-Chung Lin(a), and Ching-Ray, Chang(a)

(a)Department of Physics, National Taiwan University, No.1 Sec.4 Roosevelt Road Taipei 10617, Taiwan (b)Rearch Center for Applied Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan

Electric field assisted magnetization switching is an interesting phenomenon for future low power

spintronics devices.[1] The Two-dimensional transition metal dichalcogneides (2D TMDs) materials, a few layerd Vanadium disulfide (VS2), has been synthesized experimentally [2]. It’s intrinsic magnetism and potential applications as a high-performance functional nanomaterial attracted particular interest.

The electronic structure calculations of monolayer VS2 were performed using the projector augmented wave (PAW) method with the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) [3] which implemented in VASP code. The energy cutoff for plane-wave basis expansion was set to 400 eV. The total energies were calculated with the convergence criteria 1x10−5 eV per unit cell. The magnetic anisotropic energy (MAE) is estimated from the total energy difference between the different magnetization directions: MAE = E[100] −E[001]. In the present work we used the 16×16×1 mesh in k-point sampling. Fig.1 is a monolayer VS2. Each V atom is surrounded by six neighboring S atoms, while each S atom has three neighboring V atoms, which structure is as same as MoS2 monolayer. The calculated lattice constant of monolayer VS2 is 3.17 A.

The MAE value of VSe2 is 0.21 meV/f.u. and easy plane is parallel to surface. When applied a small perpendicular electric field about 0.03 meV/A, the MAE value changes it sign and easy plane is perpendicular to surface which is -0.78 meV/f.u.. This value is large than the MAE of 4.8×10-3 meV/f.u. Fe in the bulk system. The electric field effects on the magnetic anisotropy in VS2 are presented in Fig.2. When applied a small perpendicular electric filed make a great changes of the MAE. There are very rare materials can be reversed the magnetic orientation when applied a small electric field. We hope that this studied material has a great potential in spintronics applications.

[1] W. G. Wang, M. Li, S. Hageman, and C. L. Chien, “Electric-field-assisted switching in magnetic tunnel junctions,”

Nat Mater, vol. 11, no. 1, pp. 64-8, Jan, 2012.

[2] J. Feng, X. Sun, C. Wu, L. Peng, C. Lin, S. Hu, J. Yang, and Y. Xie, Metallic Few-Layered VS2 Ultrathin Nanosheets:

High Two-Dimensional Conductivity for In- Plane Supercapacitors. J. Am. Chem. Soc., 133, 17832-17838 (2011).

[3] J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 477, 3865 (1996).

Fig. 1. The Atomic structure of VS2 .

Fig. 2. The electric field effects on the magnetic anisotropy in VS2.

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PM-08

Spin-Fluctuation Mechanism of Insulator-Metal Transition of Strongly Correlated

Paramagnetic Compounds with pd-Hybridization

A.A. Povzner, A.G. Volkov

Ural Federal University, Ekaterinburg,620002. Russia e-mail: agvolkov@yandex.ru

Within the framework of the periodic Anderson model, we investigate the transition of strongly correlated covalent insulator with hybridization gap in the metallic state. It is shown that the hybridization of the electron spin states occurs in addition to the hybridization of p- and d-states of electrons. For this reason, the spin density d-like electrons fluctuates without breaking the singlet state of the valence band, which is separated from the conduction band of hybridization gap. Therefore, in the insulator state, the spin susceptibility is zero, but the electronic specific heat increases with temperature due to the dynamic spin fluctuations.

The temperature increase in the amplitude of spin fluctuations leads to d-like states inside the hybridization gap. This leads to an insulator-metal transition.

In metallic phase, spin susceptibility appears and increases with temperature. The number occupied d-like states none monotonically varies with temperature that generates a maximum of electronic heat capacity. Above the temperature of saturation of spin fluctuation amplitude it the spin susceptibility described by the Curie-Weiss law. Numerical calculations show that this picture is consistent with the results of experimental studies and ab initio calculations of the electronic structure of FeSi.

The figure shows no lattice component FeSi specific heat (in units of the maximum height) calculated under this approach. Points are experimental data processed in the

framework of the extended Debye model [1]. The solid line is the results of the calculation. 1 is the contribution due to the fluctuations of the occupation numbers, 2 is the contribution due to the Fermi excitations, magnified 200 times, 3 is the contribution due to paramagnons excitations.

[1] A. A. Povzner, A. N. Filanovich. Physica B 456. 371 (2015)

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PN-01

First-principles calculation of electronic structure in NiMnSb/MgO and CoMnSb/MgO junctions

M. Shirai(a), A. Onodera(a), M. Tsujikawa(a), Y. Miura(b)

(a)Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan

(b)Graduate School of Science and Engineering, Kyoto Institute of Technology, Kyoto 606-8585, Japan

Half-metallic ferromagnets are promising candidates for electrode materials of magnetic tunnel junctions (MTJ). Extensive studies have been carried out for MTJ using Co-based full Heusler alloys, such as Co2MnSi and Co2FeSi, with L21 structure. On the other hand, experimental attempt was limited for MTJ using Heusler alloys with C1b structure such as NiMnSb and PtMnSb. First-principles calculations indicated that atomic disorder gives rise to electronic states in the minority-spin gap and easily degrades the spin polarization of NiMnSb [1]. In this study, we performed density- functional calculations of electronic structure in NiMnSb/MgO and CoMnSb/MgO junctions to assess the feasibility of these Heusler alloys as electrode materials of MTJ. We adopted the Vienna ab initio simulation package (VASP) with use of the projector augmented-wave (PAW) potential. The exchange-correlation energy is considered with a generalized gradient approximation (GGA). First, we examined stable interfacial structure of NiMnSb/MgO and CoMnSb/MgO junctions by evaluating formation energy of each structure. As a result, the MnSb-terminated interface, where Mn and Sb atoms are located on top of O atoms, is preferable energetically for both junctions. While the magnetic moment of Mn atoms at the interface increases compared to that in bulk, the Ni or Co magnetic moment on the sub-interface layer remarkably decreases for both junctions. Note that the Co magnetic moment of Co2MnSi is almost unaltered even at the sub-interface layer in the MnSi-terminated Co2MnSi/MgO junction [2]. The reduction of the Ni or Co magnetic moment in the interfacial region enhances thermal fluctuation of the magnetic moment, which leads to significant reduction of tunnelling magnetoresistance (TMR) ratio with increasing temperature [3]. We also found the reduction of the spin polarization in the interfacial region of the NiMnSb/MgO and CoMnSb/MgO junctions due to the presence of interfacial resonant states in the minority-spin gap. The reduction of the spin polarization and the magnetic moment in the interfacial region of CoMnSb/MgO junction can be recovered by Co or Mn atoms occupied at the vacancy sites in the interfacial region.

This work was partly supported by a Grant-in-Aid for Scientific Research (Grant No. 25220910) from JSPS/MEXT. [1] D. Orgassa, et al., Phys. Rev. B 60, 13237 (1999). [2] Y. Miura, et al., Phys. Rev. B 78, 064416 (2008). [3] Y. Miura, et al., Phys. Rev. B 83, 214411 (2011).

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Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junction

Fa-Chieh Chu, Zhao-Wen Huang, Bao-Huei Huang, Yu-Hui Tang*

Department of Physics, National Central University, Jhong-Li, Taoyuan, Taiwan

e-mail: yhtang@cc.ncu.edu.tw

Recent discoveries in the ferromagnet/insulator/ferromagnet (FM/I/FM) magnetic tunnel junctions (MTJs) have demonstrated that the relative orientation of the two FM electrodes can be either altered by an external magnetic field, i.e. the tunneling magnetoresistance (TMR) effect, or controlled by a spin-polarized current, i.e. the current-induced magnetization reversal via the spin transfer torque (STT) effect. The spin-transfer, T||, and field-like, T⊥ , components of the STT originate from different components of the spin current accumulated at the FM/I interface and can be expressed in terms of the interplay of spin current densities and of the non-equilibrium interlayer exchange couplings [1], respectively, solely in collinear configurations.

The insulator in conventional FM/I/FM MTJs plays only a passive role in the spin-polarized transport. The evolution beyond passive components has broadened the quest for multifunctional spintronic devices consisting of spin-filter (SF) barriers [2], which exploits the separation of the barrier heights of the two spin channels that can be in turn tuned via an external magnetic field.

In this study [3], the tight binding calculations and the non-equilibrium Green's function formalism is employed to study the effect of the SF-barrier magnetization on the bias behavior of both components of STT in noncollinear FM/I/SF/I/FM junctions. We predict a giant T⊥ in contrast to conventional FM/I/FM junctions, which has linear bias dependence, is independent of the SF thickness, and has sign reversal via magnetic field switching. Our results suggest that the novel dual manipulation of T⊥ either by a magnetic field or bias can be employed for “reading＂ or “writing＂ processes, respectively, in the next-generation field-like-spin-torque MRAM (FLST-MRAMs). Finally, our newly derived general expressions of noncollinear T|| and T⊥ allows the efficient calculation of the STT from collinear ab initio electronic structure calculations [4,5]. (Contract No. NSC 102-2112-M-008-004-MY3)

[1] Y. –H. Tang et al., Phys. Rev. B 81, 054437 (2010).

[2] T. S. Santos and J. S. Moodera, Phys. Today 63, 46 (2010).

[3] Y. –H. Tang, F. –C. Chu, and N. Kioussis, Sci. Rep. 5, 11341 (2015).

[4] X. Jia, K. Xia, Y. Ke, and H. Guo, Phys. Rev. B 84, 014401 (2011).

[5] Y. –H. Tang and F. –C. Chu, J. Appl. Phys. 117, 093901 (2015).

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Optical observation of Spin wave excited by the magnetic vortex core oscillation

Ming-Yi Kao, Liang-Juan Chang, Shang-Fan Lee

Institute of Physics, Academia Sinica, Taipei, Taiwan

Magnetic vortex is a typical ground state of nanoscale magnetic thin film structure,

in which the exchange coupling is strong enough leading to the out of plane

magnetization at the vortex core with diameter of only 10 to 20 nanometer. The fast

switching of the vortex core can be achieve by acting the in-plane oscillating magnetic

field. With the magnetic field of large amplitude and oscillating at the gyration

eigenfrequency can reverse the core polarity. However, using this approach, the vortex

core is also rotating in plane with large core movement creating a severe problem for

bit reading in magnetic data storage device.

In this study, we present the strong radiation of spin waves excited by the out of

plane magnetic field induced reversal or oscillation of a magnetic vortex core. With the

oscillating out of plane field, the magnetic core will change its polarity with no

displacement. The spin wave can be emitted from the vortex core with localized large

torque employed at the core, then it can be injected in to the nanowire with different

phases. We present this results by using the OOMMF simulation in and the experiment

results is measured in magnetic microstructure made of Ni81Fe19 using the coplanar

waveguide to generate the oscillating out of plane magnetic field. The spin wave

characteristics have been measured by Brillouin light scattering microscopy.

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Effect of Ca substitution on the multiferroic properties of BiFeO3 films on glass substrates at reduced

temperature

S.Y. Lin(a), Y.C. Lo(a), K.T. Tu(a), C.R. Wang(a), C.S. Tu(b), H.W. Chang(a)*

(a)Department of Applied Physics, Tunghai University, Taichung 407, Taiwan (b)Department of Physics, Fu Jen Catholic University, Taipei 242 Taiwan

BiFeO3 (BFO) perovskite compound with both ferroelectric and magnetic

transition well above room temperature has attracted much attention in recent years due to promising applications in the advanced spintronic and memory devices[1-2]. The substitution of different valence elements for Bi in BFO provskite phase is a pronounced way to control various physical properties. Interesting structural and electrical evolutions were revealed in Bi1-xCaxFeO3 (BCFO) ceramics. [3-4] However, rare report on polycrystalline films of (Bi, Ca)FeO3 is available. In this present work, BCFO films with x = 0.05, 0.1, and 0.15 are grown on fine controlled Pt(111) electrode layer on glass substrate by pulsed laser deposition. Pt layer with t = 10-30 nm in thickness was optimized to obtain strong (111)-texture and smooth surface. 200-nm-thick BCFO films were then in-situ grown at 450 oC. BCFO films exhibit typical multiferroic properties comparable to BFO films grown on single crystal substrates. Magnetization at 1 T of 5.9-8.2 emu/cm3 with coercivity of 1224-1258 Oe are obtained, which is consistent with the result of suppressed spiral spin configuration that have been revealed. Ferroelectric polarization 2Pr of 124 μC/cm2 and coercive field Ec of 394 kV/cm are obtained for BCFO films with x = 0.05, and are almost linearly decreased with x to 91 μC/cm2 and 294 kV/cm for x = 0.15, respectively, which might be related to reduced average displacement of A site ions relative to FeO6 octahedral with Ca2+ substitution for Bi3+. The magnetic and electric properties, including ferroelectric and leakage behaviors are as functions of Ca content. Detailed results of microstructure analysis provide useful information concerning how the multiferroic properties are modified by Ca substitution.

References [1] M. Bibes et al., Nature Materials 7, 425 (2008). [2] J. Wang et al., Science 299, 1719 (2003). [3] C.H. Yang et al., Phys. Chem. Chem. Phys. 14, 15953 (2012). [4] N. Maso et al., Chem. Mater. 24, 2127 (2012).

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Room temperature electrically tunable rectification magnetoresistance in Al/Ge Schottky devices

Shi-shen Yan,* Huan-huan Li, Kun Zhang, Yu-feng Tian and Liang-mo Mei

School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China

*Email: shishenyan@sdu.edu.cn

The ability to control the resistance of a material and/or an artificial structure with external magnetic and electrical fields is of great interest to both condensed matter physics and the next generation spintronics applications. Usually, the electrical modulation of magnetotransport properties is realized through the usage of combined ferromagnetic, ferroelectric and multiferroic materials or is based on spin transfer torque exerted by a spin polarized current on the spin moment of a nanometer scale magnet. In this work, an innovative technique for electrical control of rectification magnetoresistance (RMR) has been developed by applying direct current and alternating current simultaneously to the Al/Ge Schottky devices. Rectification magnetoresistance effect comes from the simultaneous implementation of the rectification and magnetoresistance in the same devices,[1] providing an ideal platform to control magnetotransport properties by using alternating current (AC). As shown in Figure 1(a), the I-V curves of the studied Al/Ge Schottky device are remarkably modified, because of the conventional AC rectification effect. Meanwhile, the total voltage detected during the RMR measurements moves upward and even changes sign from negative to positive by applying a positive offset current while keep AC current fixed (Figure 1(b)). As a result, the rectification magnetoresistance could be tuned in the range from -530% to 32500%. More importantly, the state-of-the-art electrical manipulation technique could be adapt to other similar heterojunctions, where fascinating rectification magnetoresistance is worthy of expectation.

Figure 1. (a) The I-V curves measured under various AC amplitude, while the conventional I-V measured by using

Keithley 2400 and 2182A is marked as DC. (b) The magnetic field dependence of the detected DC voltage measured

under fixed AC and variable DC offset for the strip Al/Ge Schottky devices.

[1] K. Zhang, H. H. Li, P. Grünberg, Q. Li, S. T. Ye, Y. F. Tian, S. S. Yan, Z. J. Lin, S. S. Kang, Y. X. Chen, G. L. Liu and

L. M. Mei, "Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions", Nanoscale 5, 14249

(2015).

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Gate-controlled spin current diverter using 2D topological insulator and normal metal junction

Chen Kuo-Chin, Chang Ching- Ray

National Taiwan University, Taipei, Taiwan. e-mail: jim75142000@gmail.com

Two-dimensional topological insulator (2DTI)-normal metal (NM) junction is proposed as a spin diverter. The helical edge state of 2DTI hybridized with the quantum well state of normal metal is well studied in this article. The helical edge state near contacted edge penetrates to NM via spin independent coupling that preserving time reversal symmetry and flows into the NM lead while the isolated edge state flows into 2DTI lead. Energy gap will be opened for one spin thus reducing the spin current for NM channel and the preserving of time reversal symmetry makes the whole spin channels to be complementary. By modulating the Fermi energy for gate control, it is possible to convert the quantum spin hall system into a spin diverter.

(Left figure) Schematic of spin current diverter composed of 2DTI-NM junction. Attaching normal metal makes helical electron near it (spin up electron) penetrating to lead2 that preserves the time reversal symmetry and the spin-momentum locking behaviour of isolated 2DTI ref (1,2), while the helical state of isolated edge (spin down electron) remain transport along the isolated edge. (Right figure) Band structure of composite system of 2DTI and NM in the region near

Fermi energy. The band dispersion of spin up and down in 2DTI are degenerated for

isolated stripe of 2DTI ref (1,2). The transmission from lead1 to lead2 (NM channel),

in the same energy region of band structure. The red line is the transmission of spin up,

blue line of spin down, and black line of charge. [1] X.-L. Qi and S.-C. Zhang, Reviews of Modern Physics 83, 1057 (2011), Topological insulators and superconductors. [2] M. König, S. Wiedmann, C. Brüne, A. Roth, H. Buhmann, L. W. Molenkamp, X.-L. Qi, and S.-C. Zhang, Science 318, 766 (2007), Quantum Spin Hall Insulator State in HgTe Quantum Wells. [3] H.-H. Lee, J.-Y. Liu, C.-R. Chang, and S.-Q. Shen, Phys. Rev. B 88, 195149 (2013), Impurity influence in quantum spin Hall transport.

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Micromagnetic Study of Spin-torque Nano-oscillators Dipolar-coupled with a Perpendicular Magnetized Layer

Ching-Ming Lee*, Yuan-Yi Liao, Te-ho Wu*

Graduate School of Materials Science, National Yunlin University of Science and Technology, Douliou, 64002, Taiwan, R. O. C.

Email:cmlee@yuntech.edu.tw,wuth@yuntech.edu.tw

We studied the frequency and linewidth of a spin torque nano-oscillator dipolar-coupled with a perpendicular magnetized layer by micromagnetic simulations. The results show that the non-uniform stray field will break the quasi-uniform precession mode which leads to the reduction of operable current range and broadening the linewidth at T=0 K. However, at T=300 K, under small current amplitude the thermal noise was reduced by the feedback from the coupled magnetic layer and thus reduce the linewidth.

[1] Z. Zeng, G. Finocchlo and H. Jiang, Nanoscale, 5, 2219-2231 (2013). [2] H.-H. Chen, C. M. Lee, J. C. Wu, L. Horng, C. R. Chang, and J. H. Chang, J. Appl. Phys. 115,134306 (2014). [3] K. Kudo, H. Suto, T. Nagasawa, K. Mizushima, and R. Sato, J. Appl. Phys. 116, 163911 (2014). [4] P. M. Braganca, B. A. Gurney, B. A. Wilson, J. A. Katine, S. Maat and J. R. Childress, Nanotechnology 21, 235202 (2010). [5] H. Arai, et al., J. Magn. Soc. Jpn. 37, pp. 218-221(2013). [6] K. J. Lee, O. Redon, and B. Dieny, Appl. Phys. Lett. 86, 022505 (2005). [7] D. Houssameddine, et al., Nature Mater. 6, 447 (2007). [8] [13] I. Firastrau, et al., Phy. Rev. B 78, 024437 (2008). [9] A. Vansteenkiste, J. Leliaert, M. Dvornik, M. Helsen, F. G.-Sanchez and B. V. Waeyenberge, AIP Advances 4, 107133 (2014). [10] J. Z. Sun, IBM J. Res. Dev. 50, 81 (2006).

Fig.1: Schematic draw of an STNO composed of a pinned layer (PL) and a free layer (FL), with a perpendicular magnetized layer (ML) beneath it.

Fig.2 Summary of the effects of PML and temperature on the relations of the STNO frequencies with the applied current amplitude.

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Spin-orbit torque in Pt/CoNiCo/Pt symmetric devices

Meiyin Yang(a), Kaiming Cai(a), Hailang Ju(b), Kevin William Edmonds(c), Guang Yang(d), Shuai Liu(b), Baohe Li(b), Bao Zhang(a), Yu Sheng(a), ShouguoWang(d), Yang Ji(a)

& Kaiyou Wang(a)

(a)SKLSM, Institute of Semiconductors, CAS, P. O. Box 912, Beijing 100083, People’s Republic of China

(b)Department of Physics, School of Sciences, Beijing Technology and Business University, Beijing 100048, China (cSchool of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom

(d)Department of Materials Physics and Chemistry, University of Science and Technology Beijing, 100083, China

e-mail: kywang@semi.ac.cn

Current induced magnetization switching by spin-orbit torques offers an energy-efficient means of writing information in heavy metal/ferromagnet (FM) multilayer systems. The relative contributions of field-like torques and damping-like torques to the magnetization switching induced by the electrical current are still under debate. Here, we describe a device based on a symmetric Pt/FM/Pt structure, in which we demonstrate a strong damping-like torque from the spin Hall effect and unmeasurable field-like torque from Rashba effect. The spin-orbit effective fields due to the spin Hall effect were investigated quantitatively and were found to be consistent with the switching effective fields after accounting for the switching current reduction due to thermal fluctuations from the current pulse. A non-linear dependence of deterministic switching of average Mz on the in-plane magnetic field was revealed, which could be explained and understood by micromagnetic simulation

Fig. 1: (a) Device structure. (b) Anomalous Hall resistance loop under a perpendicular magnetic field. (c) Current distribution around the disk obtained by finite element calculation. Red arrows indicate the direction and magnitude of the current density. (d) The current distribution projected along x axis.

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Hyperfine structures and magnetic properties of MnxGa alloys

A. Koeba, T. Shima and M. Doi

Graduate school of engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo 985-0862, Japan

e-mail: s1594304@g.tohoku-gakuin.ac.jp

Permanent magnets have been used in many applications such as sensors, generator of wind turbine and motors of hybrid vehicle. Recently, demand of these products are intensively increasing, since it’s activities have a strong effects for energy saving. In addition, the development of new permanent magnets having superior properties regardless of resources problem is strongly desired. Mn based alloys well known that it exhibits a high magnetocrystalline anisotropy (1.0-1.5 ×107 erg/cm3) [1]. That also purposes possibility as the new permanent magnets. However, there are few reports of detail of hyperfine magnetic structure of MnxGa based alloys. In this work, in order to obtain the design guideline for new permanent magnets of Mn based alloys with high saturation magnetization, hyperfine magnetic structure of Fe in MnxGa alloys has been investigated by Mössbauer spectroscopy. MnFexGa alloys have been prepared by arc melting in argon atmosphere. The base pressure of arc melting was less than 10-2 Pa. All samples were melted at five times to perform homogenization. Then, the samples were powdered by diamond file. Subsequently, the powders have been vacuum sealing in a quartz tube and annealed from 350 to 650 to get L10 phase, D022 phase and D019 phase structure[2]. The structural analysis was performed by powder X-ray diffraction (XRD). Composition of these samples was analyzed by Energy Dispersive X-ray spectroscopy (EDX). Magnetic properties were measured by using a vibrating sample magnetometer (VSM) function of physical property measurement system (PPMS) apply a magnetic field of ± 80 kOe. The hyperfine magnetic structure was characterized by conventional Fe57 Mössbauer spectroscopy.

Mn3-xFexGa alloys have obtained the D022 and D019-single phase. From the Mössbauer analysis of the samples for D022-single phase, the preferential substitution of Fe in Mn Ⅱ site was clearly observed and the hyperfine field at Mn Ⅱ site showed considerably low from the Mössbauer analyses of the samples for D022-single phase. Also, the transition of magnetic state of the Fe in D019-phase alloys has been clearly observed by the hyperfine field. In addition to the above-mentioned result, hyperfine field of Fe in L10 phase was investigated and compared with hyperfine field of D022 and D019 phase. The detail will be reported on the conference. [1] S. Mizukami, T. Kubota, F. Wu, X. Zhang, and T. Miyazaki, IEEE Trans. Magn. 85, (2012) 014416. [2] K. Minakuchi, R. Y. Umetsu, K. Ishida and R. Kainuma, J. Alloys Compd. 537, (2012) 332-337.

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Synthesis of Mn-Bi Alloy using a Quenching Furnace under High Magnetic Fields

Misaki Yamashita(a), Kenichi Abematsu(a), Khoki Takahashi(b), Yoshifuru Mitsui(a), Keiichi Koyama(a)

(a) Graduate School of Science and Engineering, Kagoshima University,

Kagoshima,890-0065, Japan (b) Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan

e-mail: k2051050@kadai.jp

It is well known that magnetic field affects crystal orientation, diffusion coefficient, phase equilibrium of magnetic materials. In order to develop the high performance magnetic materials using magnetic field, the heat treatments under high magnetic fields is one of the key technique.

Recently, the magnetic and microstructural properties of ferromagnetic MnBi have been of interest. The peritectic temperature ferromagnetic MnBi increased in the rate of 2 K/T with increasing magnetic field [1]. Quite recently, Mitsui et al. found that synthesis of ferromagnetic MnBi by solid-state reaction sintering method was promoted by application of the high magnetic fields [2]. It has been well known that obtaining the single-phase sample is very difficult because MnBi is an incongruent-melting material and has the lower eutectic temperature of 535 K. Therefore, it is required to use a furnace with quenching bath in the small bore of a high field magnet, in order to synthesize high quality MnBi magnets. However, there is no report that Mn-Bi alloy was prepared by in-field quenching yet.

In this study, we developed a small furnace with quenching bath, which was utilized for high-field magnets with a 50-mm room-temperature bore. In our furnace, the quenching speed was within 20 seconds from 773 K to 373 K under a magnetic field of 8 T. X-ray diffraction (XRD) measurement was carried out for evaluation of samples. It was confirmed that the XRD patterns for in-field quenching sample was different from that for slow-cooling sample in magnetic field. Obtained results suggested that in-field quenching was one of the useful methods for synthesizing high performance magnetic materials.

[1] Koyama et al., J. Alloys and Comp. 509 (2011) L78-L80. [2] Mitsui et al., J. Alloys and Comp. 615 (2014) 131-134.

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Comparison of hydrogen decrepitation behaviors between (La, Ce)-Fe-B and Nd-Fe-B strips

Jiaying Jin, Yujing Zhang, Guohua Bai, Tianyu Ma, and Mi Yan

School of Materials Science and Engineering, State Key Laboratory of Silicon materials, Key Laboratory of Novel Materials for Information Technology of

Zhejiang Province, Zhejiang University, Hangzhou 310027, China e-mail: jjy_zju@163.com

The escalating cost of Nd coupled with its limited availability has recently spurred researches featuring the substitution of Nd by high-abundant and low-cost La and Ce [1]. As hydrogen decrepitation (HD) is widely adopted to crush the cast strips into powders when preparing 2:14:1-type sintered magnets, La-Ce substitution for Nd, however, may exert complex influences on the HD behavior. Understanding the influence of La/Ce substitution on the microstructure and fracture mechanism of strips is of great significance in the mass production of La/Ce-containing 2:14:1-typed magnets and hence requires in-depth investigations. In this work, La-Ce alloy (35 wt. % La and 65 wt. % Ce) is employed to prepare (La, Ce)-Fe-B strips via strip casting, as a comparison to the traditional Nd-Fe-B strip. Temperature vs. hydrogen pressure plots in Fig. 1(a) are obtained by exposing the samples to pure hydrogen environment with changing pressure from 2.5 to 5.5 MPa. The Nd-Fe-B strip possesses a most obvious reaction exothermic effect during hydrogen absorption, compared to the (La, Ce)-Fe-B ones. In terms of (La, Ce)-Fe-B strips placed at 2.5 MPa, two reaction peaks can be observed as illustrated in the upright inset, suggesting a two-step hydrogen absorption reaction. Further increasing the pressure to 4.0 and 5.5 MPa, only one peak can be detected, whereas the peak intensities remain basically unchanged. Dependence of the corresponding weight increase on the pressure is shown in Fig. 1(b). It is revealed the hydrogen absorption behavior of (La, Ce)-Fe-B strips can be slightly enhanced with increasing pressure, which though are still inferior to that of Nd-Fe-B system.

[1] O. Gutfleisch, M. A. Willard, E. Brück, C.

H. Chen, S. G. Sankar, and J. Ping Liu, Adv.

Mater, 23, 821 (2011).

Fig. 1. (a) Temperature vs. hydrogen

pressure plots and (b) weight

increase obtained from (La,

Ce)-Fe-B and Nd-Fe-B strips.

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Structure and magnetic properties of FeCoAlBN soft magnetic films prepared by pulsed laser deposition

Guohua BAI, Chen WU and Mi YAN School of Materials Science and Engineering, Zhejiang University, Hangzhou

310027, China e-mail: jason_bai@live.com

FeCo-based metal-insulator films with FeCo nanocrystalline composited with insulator such as Al2O3, MgF2 and SiN have been found to exhibits high resistivity and satisfactory high frequency magnetic properties [1-3]. In this work, FeCoAlBN films have been prepared by reactive pulsed laser deposition (PLD) and influences of nitrogen doping have been investigated. The results shows that excellent magnetic properties with coercivity of 6 Oe, in-plane anisotropy of 70 Oe and ferromagnetic resonance frequency of 2.1 GHz can be obtained, indicating great potential of the film for high frequency applications.

[1] Yan Liu, C. Y. Tan, Z. W. Liu, C. K. Ong, Appl. Phys. Lett., 90, 112506 (2007)

[2] J.C. Sohn, D.J. Byun, S.H. Lim, J. Magn. Magn. Mater. 272–276, 1500–1502 (2004)

[3] Dongsheng Yao, Shihui Ge, Bangmin Zhang, Huaping Zuo, and Xueyun Zhou, Journal of Applied

Physics 103, 113901 (2008)

Fig. 1 Ms and dependence of N2 pressure. Inset: HRTEM image of FeCoAlBN film prepared with PN2 = 2 mtorr

Fig. 2 M-H loops and permeability spectrum (inset) for the FeCoAlBN film (PN2 = 2 mtorr)

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Novel fabrication method of soft magnetic thin ribbons

K. Eguchi, K. Azuma, T. Akiyoshi, T.Yanai, M. Nakano, H. Fukunaga

Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan e-mail: bb35212009@ms.nagasaki-u.ac.jp

It is well-known that a reduction in thicknesses of soft magnetic materials is one of

effective methods to reduce an eddy current loss, and soft magnetic thin ribbons are widely used for high-frequency driven electric machines. Typical soft magnetic thin ribbons are produced by rapid quenching methods, and their thicknesses are approximately 20 m. In present study, we proposed a novel fabrication method of soft magnetic thin ribbons (< 15 m) using an electroplating method, and evaluated the ac magnetic properties of the thin ribbons.

We electroplated Fe-Ni thin films on a Cu sheet (L350 × W3 × T0.3 mm), and then the films were peeled off physically from the Cu sheet. The bath composition and plating conditions were determined based on our previous study [1, 2]. The ribbon was formed into a toroidal core, and we evaluated ac magnetic properties of the core. The maximum applied field was fixed at 1 kA/m, and we obtained the coercivity from the ac B-H loop. Figure 1 shows thickness of the ribbon as a function of plating time. The thickness increases proportionally with increasing the plating time. The insets show the peeled ribbon and the cross-sectional area obtained by a SEM observation. The SEM image suggests that the ribbon is high dense (no porous). Figure 2 shows the frequency dependence of the coercivity. In high freqency range, the 5 m-thick ribbon shows much lower coercivity value compared with other ribbons, and we confirmed the effect of the thickness on magnetic properties. In conclusion, the electroplating method is one of attractive methods to fabricated soft magnetic thin ribbons. [1] T. Shimokawa et al., IEEE Trans. Magn., 48 (2012) 2907.

[2]Y. Watanabe et al., J Appl. Phys, 117 (2015) #17A326.

Fig. 1 Thickness of the ribbon as a function of plating time.

Fig. 2 Coercivity of the ribbon as a function of frequency.

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Fig.1 Jr and Hc as a function of Pr contents in each film.

Rare earth thick film magnets deposited on glass substrates for MEMS application

K. Hirotaki(a), A. Yamashita(a), M. Nakano, (a) T. Yanai(a), R. Fujiwara(b), T. Shinshi(b), and H. Fukunaga(a)

(a)Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan

(b)Interdisciplinary Graduate School of Science and Engineering,

Tokyo Institute of Technology, Yokohama 226-8503, Japan e-mail: bb52115243@ms.nagasaki-u.ac.jp

Rare earth permanent magnet films thicker than 10 µm were hopeful materials

applied for MEMS, however almost all the samples have been deposited on Si or glass

substrates with a metal buffer layer [1][2]. In this study, the preparation of Pr-Fe-B

thick films on glass substrates without a buffer layer was carried out. This contribution

reports the evaluation on the magnetic and mechanical properties in each film with

different Pr contents. Each film was deposited on a glass substrate by using a YAG

pulse laser (λ : 355 nm, frequency : 30 Hz) in the vacuum atmosphere of 2 ×10-5 Pa.

The laser beam was focused on the surface of a PrXFe14B(X=1.8, 2.0, 2.2, 2.4) target

under the deposition rate higher than 10 μm/h. A pulse annealing (PA) method enabled

us to crystallize hard magnetic phase. Figure 1 shows the magnetic properties as a

function of Pr contents in each film thicker than 10 µm. As the amount of Pr increased,

coercivity increased and residual magnetic polarization decreased. We have already

reported that Nd(or Pr)-Fe-B thick films with rare-earth amount less than 15 at. %

deposited on Si substrates were broken after a post annealing process [3], however the

Pr amounts could be reduced down to approximately 13 at. % without the deterioration

of mechanical properties on glass substrates. It was also confirmed that an

approximately 100 µm-thick Pr-Fe-B thick film with (BH)max of about 80 kJ/m3 could

be deposited on a glass substrate.

[1] Y. Zhang et al., Acta Materialia, 60,

3783-3788 (2012).

[2]C. Zhi et al., International. J. Automation

Technplogy, 7, 196-204(2013).

[3] M. Nakano et al., IEEE Trans. on Magn.,

51, #2102604-1〜4(2015).

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DC/pulse plating of Fe-Ni-Co films

K. Eguchi, K. Azuma, T. Akiyoshi, T. Yanai, M. Nakano, H. Fukunaga

Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan e-mail: bb35212009@ms.nagasaki-u.ac.jp

Fe-Ni-Co ternary alloys are attractive soft magnetic materials, and we have reported a flux gate sensor with an electroplated Fe-Ni-Co film [1]. For improvement in robustness of the sensor output against the temperature variation, an increase in Co content of the film are effective since the Curie temperature increases with increasing the Co content. In the present study, we electroplated Fe-Ni-Co films focusing on the Co content, and evaluated the magnetic and the structural properties.

We employed a DC and a pulse plating methods. The bath composition and the plating conditions were determined based on our previous study [1, 2]. The Fe content in the as-plated films were kept at approximately 20 at.%.

Figure 1 shows the coercivity as a function of Co content. The coercivity shows almost constant values up to Co 40 at.% for the DC plating and 60 at .% for the pulse one. In order to investigate the effect of the pulse plating on the coercivity, we evaluated the film surface. Figure 2 shows the SEM images of the Fe-Ni-Co films with various Co content. Large difference between the DC plating and the pulse one was observed at Co 45 at.%, and smooth surface was obtained by the pulse plating. As a rough surface is a factor to deteriorate magnetic properties in typical soft magnetic materials, we concluded that the pulse plating is more attractive than the DC plating for fabrication of Fe-Ni-Co films with low coercivity and high Curie temperature. [1] Y. Watanabe et al., IEEE Tran. Magn., 51 (2015) #4004104.

[2] T. Yanai et al., “Effects of annealing and pulse plating on soft magnetic properties

of electroplated Fe-Ni films”, AIP Advances, (2016.5) to be published.

10 20 30 40 50 60

20

40

60

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100

0

Co/(Fe+Ni+Co) [at.%]

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rciv

ity

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]

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15 m

Fig. 1 Coercivity of the Fe-Ni-Co film as a function of the Co content.

Fig. 2 SEM images of the Fe-Ni-Co films with various Co content.

B-252

PO-08

Local geometric and electronic structures, and magnetic

properties of Mn-doped SrTiO3

T. L. Phan(a), N. Tran(a), B. W. Lee(a), T. A. Ho(b), T. D. Thanh(c), S. C. Yu(c) (a)Department of Physics and Oxide Research Center, Hankuk University of Foreign

Studies, Yongin 449-791, South Korea (b)Department of Materials Science and Engineering, Korea University, Seoul 136-713,

South Korea (c)Institute of Materials Science, Vietnam Academy of Science and Technology, Hoang

Quoc Viet, Cau Giay, Hanoi, Vietnam e-mail: ptlong2512@yahoo.com

We prepared polycrystalline-ceramic samples of SrT1-xMnxO3 (x = 0-0.1) by using

conventional solid-state reaction. X-ray diffraction and Raman scattering studies

revealed the incorporation of Mn dopants into the cubic SrTiO3 structure. More

detailed analyses of X-ray absorption spectra proved these Mn dopants having

oxidation states of 2+ and 3+, which located at the Ti site. Basically, Mn2+ ions are

usually dominant in the samples with low Mn-doping concentrations. Increasing Mn

concentration leads to the valence shift of Mn2+ → Mn3+. This can be seen clearly from

the shift of absorption edges towards higher energies of Mn2O3 (associated with Mn3+)

when Mn concentration increases. The valence change of Mn results in the different

features and parameters of ESR spectra. Particularly, for the samples with low Mn

contents, hyperfine sextet lines of isolated Mn2+ ions are dominant. The additional

presence of Mn3+ ions promotes dipolar interactions between Mn2+ and Mn3+. This

leads to the appearance of a broad resonance line in the Lorentzian shape,

corresponding to the background-broad line. Besides the resonant signals generated

from isolated Mn2+ ions and/or dipolar exchange interactions, there also exists a

resonant signal of intrinsic defects. With the recorded experimental results, we suggest

that the coexistence of intrinsic defects and Mn ions at a suitable concentration (with x

> 0.02) is an important pivot of weak ferromagnetism in SrTi1-xMnxO3.

B-253

PO-09

Magnetic-field driven second-order phase transition to the first order in Pr-doped La0.7Ca0.3MnO3

T. L. Phan(a), P. T. Tho(a), C. L. Liu(a), T. A. Ho(b), S. H. Lim(b)

(a)Department of Physics and Oxide Research Center, Hankuk University of Foreign

Studies, Yongin 449-791, Korea (b)Department of Materials Science and Engineering, Korea University, Seoul

136-713, South Korea e-mail: ptlong2512@yahoo.com

Perovskite manganites, R1-xA’xMnO3 (R = La, Pr, Nd; and A’ = Ca, Sr, Ba), are still of intensive interest because of exhibiting colossal magnetoresistance (MR) and magnetocaloric (MC) effects. To explain these phenomena, theoretical models of exchange interactions, polarons, and phase separation combined with the percolation and Griffiths singularity have been proposed. It has been agreed that colossal MR and MC effects are related to ferromagnetic (FM) or antiferromagnetic (AFM) ordering, charge ordering, and orbital ordering; meaning the interplay of spin, orbital and lattice/phonon degrees of freedom. These properties found in R1-xA’xMnO3 compounds are dependent on concentration of Mn3+ and Mn4+ ions. A coexistence of Mn3+ and Mn4+ ions leads to the FM interaction associated with a Mn3+-Mn4+ pair, and the AFM associated to Mn3+-Mn3+ and Mn4+-Mn4+ pairs. With R = La, the FM interaction, and colossal MR and MC effects usually become largest as Mn3+/Mn4+ = 7/3. Below and above this value, AFM interactions are dominant. Among La0.7A’0.3MnO3 compounds, La0.7Ca0.3MnO3 (LCM) has attracted much more interest because its FM-PM phase transition is followed up with structural changes is discontinuous, which is known as a first-order magnetic phase transition (FOMT). This phase transition can be modified to a continuous second-order phase transition (SOMT) upon quenched disorder that can be carried by doping suitable elements into the Mn and/or La/Ca sites. To further understand this problem, we prepared LCM and La0.2Pr0.5Ca0.3MnO3 (LPCM) by solid-state reaction, and then studied their magnetic properties. We point out that while LCM always exhibits the FOMT, LPCM exhibits the SOMT at magnetic fields below 12 kOe, with the critical exponent close to that expected for the mean-field theory. At higher magnetic fields, however, there is the SOMT-FOMT transformation, leading to a strong variation of the Curie temperature (TC), and the parameters related to the MC effect. We believe that the nature of these phenomena is related to structural changes, Griffiths phase, and magnetic contributions of Pr3+ ions because the ratio Mn3+/Mn4+ is unchanged.

B-254

4th August, Thursday

B-255

FA-01

Quantum anomalous Hall phases in layered magnetic oxides predicted by first-principles density functional

calculations

Guang-Yu Guo

Department of Physics, National Taiwan University, Taipei 10617, Taiwan

Quantum anomalous Hall (QAH) phase is a two-dimensional bulk ferromagnetic

insulator with a nonzero Chern number usually in presence of spin-orbit coupling

(SOC). Associated metallic chiral edge states carry dissipationless current transport in

electronic devices. Due to its intriguing nontrivial topological properties and great

potential application for designing dissipationless spintronics, extensive theoretical and

experimental studies have been made to search for real materials to host such QAHE.

Indeed, this intriguing QAH phase has recently been observed in magnetic impurity-

doped topological insulators, albeit, at extremely low temperatures [1].

Based on first-principles density functional calculations, we predict that the QAH

phases would exist in two kinds of layered 4d and 5d transition metal oxides at high

temperatures [2-3]. Furthermore, theoretical analysis reveals that the QAH phases in

these oxide systems originate from two distinctly different mechanisms [2-3].

[1] C.-Z. Chang et al., Science 340, 167 (2013) [2] J. Zhou et al., arXiv:1602.08553 (2016) [3] H. K. Chandra and G. Y. Guo, arXiv:1512.08843 (2015)

B-256

FA-02

On searching for 2-dimensional (2D) magnetic semiconductors based on 2D Transition-Metal

Dichalcogenides (TMD) : ICAUMS 2016

Huei-Ru Fuh (a), Kai-Wei Chang (b) , Horng-Tay Jeng (c)

(a) Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan

(b) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (c) Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

e-mail: jeng@phys.nthu.edu.tw

The next generation spintronic devices can base on room temperature ferromagnetic

semiconductors or heterostructures combining ferromagnetic metals with nonmagnetic

semiconductors. Nevertheless searching for semiconducting materials with strong

ferromagnetism and higher TC is extremely difficult due to the conflicting

requirements in the crystal and electronic structures of semiconductors and

ferromagnets. To date all the discovered ferromagnetic semiconductors such as EuO,

BiMnO3, La2NiMnO6, and diluted magnetic semiconductor (Ga, Mn)As exhibit

magnetic order below the room temperature. The only exception is the ferrimagnetic

insulator Y3Fe5O12 (YIG) with a very high Tc = 550 K far beyond room temperature.

This is the reason why most of the spintronics related works rely on YIG. Meanwhile

all the known magnetic semiconductors belong to 3-dimensional (3D) bulk materials.

In this work we focus on searching for 2D magnetic semiconductors based on the

transition-metal dichalcogenides (TMD) family. We successfully discovered several

2D magnetic semiconductors among the TMD family. Moreover few of them exhibit

fairly high Tc above the room temperature.

B-257

FA-03

Roles of nonmagnetic elements in magnetic devices: first-principles studies

Soon Cheol Hong, P. Taivansaikhan, Soyoung Jekal, S. H. Rhim

Department of Physics and Energy Harvest-Storage Research Center, University of

Ulsan, Ulsan 44610, Republic of Korea

In this talk we will discuss roles of nonmagnetic elements in magnetic devices with our recent first-principles calculational results on three systems; i) Fe/MgO(001) surface capped by 4d and 5d transition metals [TM/Fe/MgO(001)], ii) metastable phase of the body-centered-tetragonal ruthenium (bct–Ru), and iii) Pd(001) and Pd(111) thin films.

In TM/Fe/MgO(001) systems, strong perpendicular magnetocrystalline anisotropies (PMCAs) are found. The origin of the extremely large PMCA will be discussed by calculating the spin-channel decomposed contribution and electronic structure analyses. Strong 3d–5d band hybridization in the minority spin state is responsible for the sign changes of the MCA from parallel to perpendicular.

A bct–Ru is identified to exhibit a large PMCA as well as an appreciable magnetic moment. The MCA energy is as large as 150 μeV/atom, two orders of magnitude greater than those of 3d magnetic metals. Further investigation over the range of tetragonal distortion suggests that the appearance of the magnetism in the bct–Ru is governed by the Jahn-Teller spit eg orbitals. Moreover, from band analysis, MCA is mainly determined by an interplay between two eg states, dx2−y2 and dz2 states, as a result of level reversal associated with tetragonal distortion.

Finally we will present thickness-dependent magnetism of Pd(001) and Pd(111) thin films. The films are found to be stable in ferromagnetic states only for certain thicknesses. Magnetization of Pd(001) and Pd(111) thin films is obviously triggered by quantum well states, rather than by surface termination. The thickness-dependent magnetism may be the origin of asymmetric magnetic behaviors observed in recent experiments.

B-258

FA-04

Electric-field Control of Skyrmion Motion

H. T. Fook, W. L. Gan, W. S. Lew

School of Physical and Mathematical Sciences, Nanyang Technological

University,Singapore.

Magnetic skyrmions in materials with Dyaloshinskii-Moriya (DM) interaction has been of intensive research due to their potential as information carriers for future skyrmion-based memory devices [1],[2]. The ability to control the perpendicular magnetic anisotropy (PMA) of such materials by electric field was observed and is envisioned to lead to low-power spintronic devices [3]. In this work, we demonstrate the control of skyrmion motion induced by electric fields applied perpendicular to the film plane. The voltage-induced skyrmion velocity scales with the change in PMA of the film and can be applied to drastically increase the velocity of current-induced skyrmion motion. Furthermore, even in the absence of a driving current, field-induced skyrmion motion is observed and reaches up to 150 m/s. One of the many possible applications of this electric-field control of skyrmion motion is a skyrmion-based shift register memory. In our proposed device, skyrmions are driven at discrete distances as a result of skyrmions trapped in potential wells created by electric gates of alternating polarity. Our analysis opens up new possibilities for the realization of extremely low-power skyrmion memory devices.

References: [1] A. Fert, V. Cros, J. Sampaio, Nature nanotechnology, 8, 152-156 (2013). [2] J. Sampaio, et al. Nature nanotechnology, 8, 839-844 (2013). [3] T. Maruyama, et al. Nature nanotechnology, 4, 158-161 (2009).

Fig. 1: Maximum skyrmion velocity as a function of change in PMA.

Fig. 2: (a) Schematic of proposed skyrmion shift register memory with two arrays of electric gates with opposite polarity. (b) Energy plot against skyrmion position in nanowire. Skyrmions are driven in discrete distances due to regularly spaced potential wells induced by the electric field.

B-259

FA-05

Enhanced anisotropic FMR linewidths under rotating magnetic fields in Fe-Si(001) single-crystal-film planes

Shinji Isogami(a), Tetsuroh Kawai(b) and Masaaki Futamoto(b) (a)Department of Physics, Fukushima National College of Technology, Iwaki-City,

Fukushima 970-8034, Japan (b)Faculty of Science and Engineering, Chuo University, Bunkyo-Ku, Tokyo 112-

8551, Japan e-mail: isogami@fukushima-nct.ac.jp

In the material design of microwave assisted magnetic recording systems,

fundamental properties about ferromagnetic resonance (FMR) must be indispensable for highly efficient magnetization switching. A paper reported that the wide and narrow FMR linewidths were observed when the magnetization pointed in the hard-axis (H.A.) and the easy-axis (E.A.), respectively [1]. In contrast, the FMR measurements for the 40-nm-thick Fe100-xSix (x = 0, 6, 10) single-crystal-films with (001) orientation [2] revealed the additional linewidth enhancement behaviours near H.A. The present study is intended to discuss the angular dependence of FMR linewidth (ΔH) in the films.

Figure 1(a) shows the resonant field (Hr) of the Fe94Si6 film as a function of the azimuthal angle of magnetic field (H). The 4-fould symmetric “bathtub-like” variation in which Hr = 1000 Oe (100 Oe) for H = <110> (<100>) was observed. The Hr was reasonably understood by the Kittel’s FMR equations, therefore, <110> (<100>) corresponded to the H.A (E.A.). Figure 1(b) shows the ΔH as a function of H. Slightly narrow ΔH for the H.A. was observed compared with that for the E.A. Moreover, note that the strong peaks up to 160 Oe were observed at ±15 deg. with respect to H.A., which peak positions were changed by the Si content. The analysis of the experimntal data requires the additional linewidth broadening mechanisms such as “field dragging” and “mosaic” contribution in our films. The influences from the Si content will be presented at the conrefence. [1] S. Isogami, et al., J. Magn. Soc. Jpn. 38, 162 (2014). [2] T. Kawai, et al., J. Appl. Phys. 117, 17A303 (2015).

Fig. 1 Experimental data of (a) resonant field (Hr) and (b) linewidth (ΔH) as a function of the azimuthal angle of magnetic field (H) for the 40-nm-thick Fe94Si4 single-crystal film. The measurements were performed using the constant 9.86 GHz microwave.

0

500

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Hr (

Oe)

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100

200

H (deg.)

H (

Oe)

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(b)

[110] [110][010] [100] [110]

H[110]

M

[110]H

M

Fe94Si6(001)

B-260

FA-06

In-magnetic-field Annealing for Mn-based alloys

Y. Mitsui(a), R. Kobayashi(a), R. Y. Umetsu(b), K. Takahashi(b), M. Mizuguchi(b), K. Koyama(a)

(a )Graduate School of Science and Engineering, Kagoshima University,

Kagoshima 890-0065, Japan (b) Institute for Materials Research, Tohoku University, Sendai 980-857, Japan

e-mail: mitsui@sci.kagoshima-u.ac.jp

Mn-based ferromagnetic alloys have been widely studied so far. Among them, MnBi and -MnAl alloys are difficult to obtain the single ferromagnetic phase because of the segregation and the co-existence of equilibrium phase.

Magnetic field stabilizes the ferromagnetic phase because of the gain of Zeeman energy to the free energy. Therefore, we have been performed the in-field heat treatment for MnBi [1-2] and Mn-Al. Additionally, crystal orientation is expected by in-field synthesis because of the magnetic crystalline anisotropy of ferromagnetic phases. In this presentation, the magnetic properties of in-field synthesized MnBi and Mn-Al were described. Fig. 1 shows the ratio of the magnetization for Mn-Al annealed in 15 T (M15T) to that in a zero field (M0T). The magnetization clearly enhanced by in-field anneal at 350ºC, indicating the enhancement of fraction of -phase. On the other hand, in-field annealing effect on the fraction of -phase was not observed at 300ºC and 400ºC. In addition, it was found that all in-field annealed bulk samples showed the isotropic magnetic properties, which was inconsistent with that for MnBi alloys [1-2]. Magnetic field effects on the synthesis of ferromagnetic MnBi and Mn-Al phases will be discussed in the presentation, in the basis of the relationship between Zeeman energy and the free energy, and the magnetic crystalline anisotropy. [1] Y. Mitsui et al., J. Alloy. Compd. 615, 131 (2014). [2] K. Abematsu et al., AIP Conf. Proc. submitted.

Fig.1. Annealing temperature dependence

of the ratio of magnetization M15T/M0T.

B-261

FA-07

Three terminal skyrmion device for memory applications

W. L. Gan, H. T. Fook, W. S. Lew School of Physical & Mathematical Sciences, Nanyang Technological

University, 21 Nanyang Link, Singapore 637371

Magnetic skyrmions possess great potential as data carriers due to their particle-like behavior that enables an additional dimension for manipulation1. However, the only skyrmion memory architecture demonstrated thus far is that of a 1D skyrmion racetrack memory in which the skyrmions were shown to move at lackluster speeds1,2. In this work, we propose a three terminal device that utilizes the extra dimension to effectively inject, delete and store skyrmions. With the addition of an extra branch, the skyrmions are injected in-line in 170 ps with an average current density of 3.8×1011 Am-2, as opposed to the tens of nanoseconds required for the magnetic field-based injection methods2.

To address the issue of low driving speeds, we exploit the spin-orbit torque (SOT) arising from a heavy metal interface to efficiently drive the skyrmion in micromagnetic simulations. In addition, we also propose a thin film structure that can induce antiferromagnetic exchange coupling between the ferromagnetic layers while still retaining the SOT interfaces. The use of synthetic antiferromagnets stabilizes the skyrmion and eliminates the Magnus force acting on the skyrmions3. We then demonstrate that the chiral skyrmion configuration can be driven at high speeds of up to 3.5 kms-1 with an applied in-plane current density by considering both the Zhang-Li spin transfer torque from the shunted current and the Slonczewski torque from the SOT.

References [1] Fert, Albert, Vincent Cros, and João Sampaio. "Skyrmions on the track."Nature nanotechnology 8.3 (2013): 152-156. [2] Woo, Seonghoon, et al. "Observation of room temperature magnetic skyrmions and their current-driven dynamics in ultrathin Co films." arXiv preprint arXiv:1502.07376 (2015). [3] I. Purnama et al., "Guided current-induced skyrmion motion in 1D potential well", Scientific Reports, 5, 10620 (2015).

Figure 2: Skyrmion velocity as a

function of applied current.

Figure 1: Electrical contacts on the

three terminal skyrmion device.

B-262

FB-01

Three-terminal Spintronics Devices for CMOS Integration

Hideo Ohnoa,b,c,d (a) Center for Spintronics Integrated Systems, Tohoku University (b) Center for Innovative Integrated Systems, Tohoku University

(c)Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University

(d) WPI-Advanced Institute for Materials Research, Tohoku University I report our effort on realizing three-terminal spintronics devices that can be used for integration with CMOS VLSI; three-terminal devices, in principle, allow higher speed and more reliable operation compared to their two-terminal counterpart [1]. Of particular interest are devices that utilize spin-orbit torque (SOT) switching, which does not require an antiferromagnetically aligned pair of magnetic electrodes like in current-induced domain wall motion devices [2]. The first topic I discuss is a high speed operation of an SOT switching device with a target ferromagnetic pillar having an in-plane magnetic easy axis collinear with the current flow direction in the underneath heavy-metal [3]. We show that one can switch magnetization as fast as 500 ps in this structure; a switching speed not readily available in two-terminal devices utilizing spin-transfer torque (STT) switching because STT requires switching current inversely proportional to the switching speed in this speed range. Another advantage of this scheme is that one can fabricate from exactly the same stack two different SOT devices; another being pillars having in-plane easy-axis but its direction perpendicular to the current direction, where conventional STT switching takes place. Using the two, we discuss the torques operating in the switching events. The second topic to be discussed is the use of an antiferromagnetic material as a source of spin flow as well as the exchange field: The former is for the switching and the latter is for the switching in the absence of external magnetic field. A small external magnetic field was required to induce SOT switching in structures other than ordinary STT switching took place, which was clearly an obstacle for future integration. It has been shown in a (Co/Ni)-multilayer/PtMn structure one can switch magnetization in the absence of external magnetic field [4]. A part of this work was supported by R&D Project for ICT Key Technology to Realize Future Society of MEXT and ImPACT Program of Council for Science, Technology and Innovation. [1] H. Ohno et al., IEDM2010, Tech. Dig., p. 9.4.1 (2010). [2] S. Fukami et al., Symp. VLSI Tech., Dig. Tech. Pap. p. 230 (2009); ibid, p. 61 (2012); Nature Commun. 4, 2293 (2013); IEDM2013, Tech. Dig., p. 3.5.1 (2013). [3] S. Fukami et al. submitted. [4] S. Fukami et al. to appear in Nature Materials (2016).

B-263

FB-02

Relativistic motion of antiferromagnetic domain walls

driven by spin-orbit torques

Takayuki Shiino(a), Se-Hyeok Oh(b), Byong-Guk Park(a), and Kyung-Jin

Lee(b,c) a. Department of Materials Science and Engineering, KAIST, Daejeon 305-701,

Korea b. Department of Material Science and Engineering, Korea University, Seoul 136-701,

Korea c. KU-KIST Graduate School of Converging Science and Technology, Korea

University, Seoul 136-713, Korea

Antiferromagnetic spintronics is attracting considerable interest nowadays as the antiferromagnet is immune to external magnetic fields [1] and compatible with metal or semiconductor electronic structure [2]. To be used as functional devices, one has to find an efficient driving force to manipulate antiferromagnet spins. The effect of spin transfer torque (STT) on antiferromagnetic spins has been identified [3]. Recently, Hals et al. [4] reported a theory of STT-induced dynamics of antiferromagnetic domain wall (AF-DW) and found that the DW velocity is proportional to the ratio between the dissipative torque and the damping, as for ferromagnet (FM) DWs.

In this talk, we report theoretical and numerical results of current-induced AF-DW motion in antiferromagnet/heavy metal bilayers where the injection of in-plane current generates spin-orbit torque (SOT). Based on the nonlinear sigma model for the Néel vector [5], we derive analytical solution of steady-state domain wall velocity. We also perform numerical computation based on atomistic spin model [6]. We find that the DW velocity increases linearly with the current for low current regimes and saturates for high current regimes. This saturation of DW velocity is caused by an emission of spin waves and consequent Lorentz contraction of DW width. As a result, the maximum DW velocity is set by the maximum group velocity of spin waves and overall DW dynamics is well described by the relativistic motion. We will discuss details of this relativistic DW motion. [1] X. Martí, I. Fina, and T. Jungwirth, IEEE Trans. Magn. 51, 1 (2015). [2] T. Jungwirth et al., Phys. Rev. B 81, 212409 (2008); P. Wadley et al., Nat. Commun. 10, 347 (2011). [3] A. S. Núñez, R. A. Duine, P. Haney, and A. H. MacDonald, Phys. Rev. B 73, 214426 (2006); Z. Wei et al., Phys. Rev. Lett. 98, 116603 (2007); S. Urazhdin and N. Anthony, Phys. Rev. Lett. 99, 046602 (2007); P. M. Haney and A. H. MacDonald, Phys. Rev. Lett. 100, 196801 (2008). [4] K. M. D. Hals, Y. Tserkovnyak, and A. Brataas, Phys. Rev. Lett. 106, 107206 (2011). [5] A. C. Swaving and R. A. Duine, Phys. Rev. B 83, 054428 (2011). [6] R. F. L. Evans et al., J. Phys.: Condens. Matter 26, 103202 (2014).

B-264

FB-03

Strain engineered magnetic tunnel junctions and spin-orbit torque switching

Xuepeng Qiu, Li Ming Loong, Kulothungasagaran Narayanapillai, Yi Wang, Jiawei Yu, Jungbum Yoon, and Hyunsoo Yang

Department of Electrical and Computer Engineering, National University of

Singapore, Singapore e-mail: eleyang@nus.edu.sg

The magnetic tunnel junction (MTJ) is a central element for the magnetoresistive random access memory (MRAM). We show that the tunneling magnetoresistance (TMR) of the MTJ is strongly influenced by strain in the tunnel barrier and ferromagnets [1,2], and demonstrate flexible MTJs on various substrates, which can be utilized for future flexible MRAM.

Current induced spin-orbit torques (SOTs) in a heavy metal/ferromagnet provide a new way to manipulate the magnetization in MTJs [3]. We examine the role of oxygen bonding in Pt/CoFeB/MgO, and find that as the oxygen bonding level increases, a full sign reversal of SOTs occurs [4], which goes beyond the bulk spin Hall effect and evidences a new SOT mechanism. We also report the angular and temperature dependence of current induced spin-orbit effective fields from Ta/CoFeB/MgO nanowires [5]. In addition, we show current induced spin-orbit torques from multilayer nanowires such as Co/Pd [6] and Co/Ni as well as oxide heterostructures such as LAO/STO [7]. The magnitude of torques is the largest obtained to date, which has important implications for future spintronic devices. Finally, we discuss the role of the Dzyaloshinskii-Moriya interaction [8] for spin orbit torque switching and SOTs in a topological insulator Bi2Se3 [9,10], which may be able to generate strong spin currents to switch the magnetization in SOT MRAM. [1] A. Sahadevan et al., Appl. Phys. Lett. 101, 042407 (2012) [2] L. M. Loong et al., Sci. Rep. 4, 6505 (2014) [3] I. M. Miron et al., Nature, 476, 189 (2011) [4] X. Qiu et al., Nat. Nanotechnol. 10, 333 (2015) [5] X. Qiu et al., Sci. Rep. 4, 4491 (2014) [6] M. Jamali et al., Phys. Rev. Lett. 111, 246602 (2013) [7] K. Narayanapillai et al., Appl. Phys. Lett. 105, 162405 (2014) [8] K. Di et al., Phys. Rev. Lett. 114, 047201 (2015) [9] P. Deorani et al., Phys. Rev. B 90, 094403 (2014) [10] Y. Wang et al., Phys. Rev. Lett. 114, 257202 (2015)

B-265

FB-04

Magnetic Chirality in the Enantiopure CsCuCl3 Crystals

K. Ohishi(a), Y. Kousaka(b), T. Koyama(b), K. Kakurai(c), V. Hutanu(d), Th. Brueckel(e), Y. Miyamoto(b), A .Sera(b), E. Proskurina(f), T. Ogura(f), A. Koda(g), K. M. Kojima(g), H. Luetkens(h), A. Amato(h), J. Suzuki(a),

K. Inoue(b), and J. Akimitsu(b)

(a)Neutron Science Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan

(b)Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan

(c)Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan

(d)RWTH Aachen University, Institut für Kristallographie, D-52056 Aachen, Germany

(e)Juelich Centre for Neutron Science JCNS-FRM II, Forschungszentrum Juelich GmbH, Outstation at FRM II, Lichtenbergstr. 1, D-85747 Garching, Germany

(f)Department of Physics and Mathematics, Aoyama-Gakuin University, Sagamihara, Kanagawa 252-5258, Japan

(g) Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan

(h) Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland e-mail: k_ohishi@cross.or.jp

Numerous experimental and theoretical studies have focused attention on chiral magnets with antisymmetric Dzyaloshinskii-Moriya interaction, because they provide opportunities to observe stable magnetic topological structure such as whirls of magnetization called skyrmions and a spiral helimagnetic order. Most of inorganic chiral magnetic materials form racemic-twinned crystals, having the right and left-handed crystalline domains in a specimen so that it is difficult to study the relation between crystallographic chirality and chirality of magnetic structures. Recently, our group succeeded in controlling the crystallographic chirality and obtained cm-sized single crystals of chiral helimagnet CsCuCl3 with homo-chirality, namely, enantiopure crystals. In order to clarify the relation between crystallographic chirality and that of magnetic structures in CsCuCl3, we performed polarized neutron diffraction and muon spin rotation measurements. These investigations revealed that there is a one to one relationship between the structural and magnetic handedness in CsCuCl3; namely the right-handed crystal structure has a right-handed spiral magnetic structure, and left-handed crystal has a left-handed spiral magnetic structure. In the presentation, we shall discuss in detail the results of the two experiments.

B-266

FC-01

Spintronics with carbon-based materials

Jung-Woo Yoo

School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Republic of Korea

e-mail: jwyoo@unist.ac.kr

Recent years witnessed increasing research activity in exploiting carbon-based materials as a spin transporting channel, which introduces a new avenue for device integration and functionality. In this talk, I will present application of an organic-based magnetic/non-magnetic semiconductor as an electron spin polarizer/spin transporting layer in the standard spintronic device geometry [1,2]. The application of organic small molecule films as the spin transporting layer has been studied extensively recently. However, conceptual understanding of how the spins are injected into and transport through these organic semiconductor films was still lacking. With careful study on film thickness, temperature, and bias dependencies, significant differences between tunneling and giant magnetoresistance were resolved. In addition, the room temperature organic-based magnet, V(TCNE)x was successfully incorporated into the standard magnetic tunnel junction devices in tandem with LSMO(La2/3Sr1/3MnO3) film [2].

The second part of this talk will be devoted for engineering spin dependent dispersion in graphene and non-local transport study therein. Graphene has been perceived to be an outstanding material for delivering spin information due to its high electron mobility and weak spin-orbit coupling. The mandatory requirement for exploiting electron spins in graphene is facile control of spin-orbit coupling. Instilling spin-orbit coupling into graphene allows splitting and detecting electron spins via spin Hall and its inverse effect. We introduced ultrathin metal pad on graphene to enhance spin-orbit coupling and studied non-local signal to demonstrate alternative spin current generation. [1] Jung-Woo Yoo, H. W. Jang, V.N. Prigodin, C. Kao, C.B. Eom, and A.J. Epstein, Phys. Rev. B 80, 205207 (2009). [2] Jung-Woo Yoo, C.-Y. Chen, H. W. Jang, C. W. Bark, V. N. Prigodin, C. B. Eom, and A. J. Epstein, Nature Materials 9, 638 (2010).

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FC-02

Giant negative magnetoresistance in Mn-substituted ZnO

X. L. Wang(a), Q. Shao(a), R. Lortz(b), J. N. Wang(b), A. Ruotolo(a)

(a)Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong

Kong, SAR China (b)Department of Physics, Hong Kong University of Science and Technology, Kowloon, Hong Kong,

SAR China

Magnetic thin films change their resistance under the application of a magnetic field. This magnetoresistive effect can be engineered to become giant by resorting to metallic multilayer devices [1,2]. An alternative route is the magnetically induced metal-insulator transition shown by strongly correlated semiconductors like mixed-valence manganites [3]. Yet, the application of these materials is limited by the difficulty and cost of fabrication. We here show that a negative magnetoresistance as large as several hundreds percent can be induced in simple zinc oxide (ZnO) doped with manganese (Mn) [4]. This anomalous effect was found to appear in oxygen-deficient films and to increase with the concentration of dopant. By combining magnetoresistive measurements with magneto-photoluminescence, we demonstrate that the effect can be explained as the result of a magnetically induced transition from hopping-type to metallic-type band conduction where the activation energy is caused by the sp-d exchange interaction.

The study was carried out on films of Zn1-xMnxO with x = 0 (pure ZnO), 0.02, 0.04 and 0.08 grown by pulsed laser deposition on sapphire substrates. The films showed n-type conductivity, regardless temperature. Oxygen vacancies (VO’s) were introduced in the films by increasing the temperature of the substrate and decreasing the oxygen partial pressure during growth. A detailed characterization of our films showed that all the Mn is in valence 2+, therefore Mn-O-Mn double-exchange interaction can be ruled out [5].

As the temperature is reduced, the resistivity of the films increases with distinct signatures of a transition from band- to hopping-conduction. A sharp decrease of resistance of the Mn-substituted films was measured when an external magnetic field was applied (see Fig. 1). The change of resistivity was found to increase with the concentration of Mn.

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Fig. 2: Normalized photoluminescence spectra of a Zn0.92Mn0.8O film in perpendicular magnetic field.

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FC-02

When a magnetic field is applied, the resistivity increases monotonically in pure ZnO while in Mn:ZnO one can distinguish three regimes that partially coexist (see Fig. 1): the resistance increases at low fields, this increase is overcome by a large decrease of resistance at intermediate fields and, finally, a linear negative magnetoresistance prevails at very high fields. The positive magnetoresistance observed at low fields depends exponentially on the applied field. This is the characteristic feature of Shklovskii’s gigantic magnetoresistance that appears in semiconductors in hopping regime [6]. As the magnetic field increases, a dramatic reduction of the resistivity is observed in Mn:ZnO that overcomes the Shklovskii’s positive magnetoresistance. We ascribe this sharp decrease to the activation of previously localized electrons on Mn-VO complexes to the conduction band because of sp-d exchange interaction.

Since ZnO is a transparent semiconductor, the magnetic activation of electrons to the band conduction can be probed by resorting to magneto-photoluminescence measurements (see Fig. 2). In fact, VO’s are optically active defect centers that can form mono centric or pair exciton complexes at low temperatures. In our films, the oxygen vacancies form deep-level F-centres, where electrons are localized when the temperature is reduced. Electrons can hop between Mn-VO complexes under the application of an electric field. An applied magnetic field reactivates the electrons in the conduction band, resulting in a sharp drop of resistivity.

Finally, at very large fields, the weak, the linear negative magnetoresistance can be simply attributed to magnetic scattering processes on paramagnetic Mn2+ ions.

The magnetoresistive effect we have reported here, although impressively large, only occurs at very low temperatures. Possible ways to bring this effect at room temperature will be discussed.

References [1] M. N. Baibich et al., Phys. Rev. Lett., 61, 2472 (1988). [2] G. Binasch et al., Phys. Rev. B 39, 4828 (1989). [3] A.-M. Haghiri-Gosnet et al., J. Phys. D: Appl. Phys. 36, R127 (2003). [4] X. L. Wang et al., Sci. Rep. 5, 9221 (2015). [5] Q. Shao, J. Appl. Phys. 115, 153902 (2014). [6] B. I. Shklovskii and A. L. Efros, Electronic properties of doped semiconductors

(Springer-Verlag, 1984)

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FC-03

Spectromicrosopic studies of defects in association with ferromagnetism of ceria based nanoparticles

Shih-Yun Chen National Taiwan University of Science and Technology, Taiwan

e-mail: sychen@mail.ntust.edu.tw

To unravel how O-vacancy defects present in ceria based nanoparticles (CeO2 NPs)

affect the band gap and relate to the magnetism, in this study, CeO2 NPs doped with

various dopant (Sm3+, Y3+ and La3+) was compared systematically by using

spectroscopic techniques (Raman, X-ray absorption (XAS) and electron energy loss

spectroscopy (EELS)) and microscopy analysis with high resolution (Scanning

transmission electron microscopy (STEM) and transmission electron microscopy

(TEM)). The doping level ranges from 0% to 15%. At first, it is demonstrated that both

type and doping level governs the formation of O-vacancy defects. At low doping level,

all dopants (Y3+, Sm3+ and La3+) randomly distributed throughout the particle. As

doping level reaches 9%, Y3+ and Sm3+ concentrate at surface to form Y-rich clusters

and a (CexSm1-x)O2-y layer, respectively. However, the aggregation was not observed in

heavily La doped NPs. The relation among dopant, O-vacancy defect structure and the

subsequent distribution of Ce3+ was demonstrated by STEM/EELS and interpreted by

the variant ionic size of dopant and defect formation energy. Magnetic analysis

indicated that in these three doped systems, ferromagnetism was contributed by some

of the Ce3+ ions. The rest of Ce3+ ions and, if present, the Sm3+ ions result in the

paramagnetism. The magnetism intensity of CeO2 NPs is related to the amount of Ce3+

at the surface and the clustering behavior of the dopant. These features plead for the

presence of a defect band at the surface, which was observed by photoluminescence

(PL) and was believed to be at the origin of the ferromagnetism.

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FC-04

Magnetic micro-/nano- structures for bio-applications H. T. Huang, C. Y. Huang, and Z. H. Wei*

Department of Power Mechanical Engineering, National Tsing Hua University, Taiwan

e-mail: wei@pme.nthu.edu.tw

Magnetic micro-/nano- structures were designed and fabricated in our study for biomedical applications such as single cell detection and single cell manipulation.

First, the three dimensional micro-/nano- structures were proposed as biosensors. This 3D magnetic sensors can actively attract the magnetically labeled cells to the sensor position and fix the cells to be detected, which is advantageous over tradition nanowire biosensors. Besides, a Wheatstone bridge giant magnetoresistance (GMR) biosensor was also proposed here for the detection and counting of magnetic cells. By the integration of the highly-developed spintronics and microfluidics, we developed an alternative technique that is more economical than flow cytometer, which is one of the most important instruments in the field of basic and clinical medicine.

Second, manipulating cells in specific positions is a very important issue for cell scaffold applications. In this study we demonstrated the cell patterning through controlling the micromagnetic states and a magnetic microstructures. In the cell patterning study, by controlling the positions of magnetic domain walls in patterned magnetic thin films, the patterning of magnetic cells can be achieved. We also demonstrated that self-assembling of magnetic fluid or microdroplets can be used to form periodic lattice structures with large area. It was employed for cell culture scaffolds. The research results can be applied to tissue engineering.

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FC-05

Enhanced Magnetic Ordering of F4-TCNQ on Ni Surface

Ming-Wei Lin (a), Po-Hong Chen(a),(b), Yu-Ling Lai(a), Der-Hsin Wei(a), and Yao-Jane Hsu(a)

(a) National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu

Science Park, Hsinchu, Taiwan (b) Department of Engineering and System Science, National Tsing Hua University,

Hsinchu, Taiwan e-mail: yjhsu@nsrrc.org.tw

Thexorbitalxhybridizationxbetweenxorganicxmoleculex2,3,5,6-tetrafluoro-7,7,8,8

-tetracyanoquinodimethane (F4-TCNQ) and ferromagnetic nickel (Ni) metals via conspicious bidirectional charge transfer induces organic magnetization. Figure 1(a) shows the surface magnetic anisotropy performed by the magneto-optical Kerr effect (MOKE) displays magnetic hardening in longitudinal plane upon F4-TCNQ adsorption, especially at low coverage Ni surface (9 ML). The magnetic domains inspected by photoelectron-emission microscope (PEEM) measurements also shown in Fig. 1(b) exhibits improved magnetic ordering at 9 ML Ni with larger domain sizes and less domain boundary. The X-ray Magnetic Circular Dichroism (XMCD) reveals the orbital and spin moment of in-plane Ni is significantly increased (MCD increase from 2.32% to 5.96% and 0% to 4.9% when F4-TCNQ deposited on at 9 and 20ML, respectively), while that keep almost unaltered at out-of-plane. The increased in-plane MCD can be also found in N in F4-TCNQ when F4-TCNQ deposited on 9 and 20ML Ni. (MCD increase from 0% to 4.9% and 9.31% to 11.1% when F4-TCNQ deposited on at 9 and 20ML, respectively) The hybridization yields an improved magnetic order at interface that might faciliate the spin injection and transport in spintronic devices. [1] Y. J. Hsu, Y. L. Lai, C. H. Chen, Y. C. Lin, H. Y. Chien, J. H. Wang, T. N. Lam, Y. L. Chan, D. H. Wei, H. J. Lin and C. T. Chen, J. Phys. Chem. Lett., 4, 310 (2013). Fig. 1 (a) The Hc value of LMOKE and PMOKE when F4-TCNQ on 9 and 20ML Ni. (b) The PPEM image of 3Å F4-TCNQ on 9 and 20ML Ni.

+phase 9.9

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Hc of LMOKE (F4-TCNQ on 9ML Ni) Hc of PMOKE (F4-TCNQ on 9ML Ni) Hc of PMOKE (F4-TCNQ on 20ML Ni)

Hc of LMOKE can not be found for 20ML Ni

(a)

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FC-06

Surface morphology, magnetism and chemical state of Fe coverage on MoS2 substrate

Hung-Chang Hsu(a), Chii-Bin Wu(b), Kai-Lin Hsu(a), Po-Chun Chang(a), Tsu-Yi Fu(a), Venkata Ramana Mudinepalli(a), Wen-Chin Lin(a)

(a) Department of Physics, National Taiwan Normal University, Taipei 11677,

Taiwan (b) Department of Physics, Chung Yuan Christian University, Chungli 32023,

Taiwan e-mail: wclin@ntnu.edu.tw

The surface morphology, magnetism and chemical state of Fe coverage on the

surface of molybdenum disulfide (MoS2) were investigated using scanning tunneling microscopy, magneto-optical Kerr effect, and depth-profiling X-ray photoemission spectroscopy (XPS). Fe deposition on the MoS2 substrate resulted in a nanoparticle array with the particle size ranged few nanometers (∼3±1 nm). For low-coverage Fe deposition <6 ML, nanoparticles were well-separated and long-range magnetic ordering was absent at room temperature. When the Fe coverage was increased, in-plane magnetic anisotropy was observed and the magnetic coercivity increased monotonically. The depth-profiling XPS showed the presence of a pure Fe state without observable chemical shift at the Fe/MoS2 interface. The XPS measurement of Pd/2 ML Fe/MoS2 also confirmed the dominance of the pure Fe state at the interface. The increase in Fe coverage changed the morphology from a nanoparticle array to a continuous coverage, leading to the onset of the ferromagnetic ordering and the transition from continuous surface oxidation to a bilayer structure.

B-273

PP-01

Direct Probe of the Spin-momentum locking Effect of NiFe/BiSe Topological Insulator Device

Yu-Jung Chen (a) , Pei-Yu Chuang(a) , Shu-Jui Chang(a), Cheong-We Chong (a) , Jung-Chun-Andrew Huang (b) , and Yuan-Chieh Tseng(a)*

(a) Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (b) Dept. Materials Science & Engineering, National Chiao Tung University,

Hsinchu, Taiwan. e-mail:perrychen25@gmail.com; yctseng21@mail.nctu.edu.tw

Topological insulator (TI), characterized by spin-momentum locked edge modes, is a fantastic candidate for the future spintronic device. In this work we demonstrate the use of an in-situ electrical & x-ray magnetic spectroscopy technique to investigate the spin-momentum locking (SML) effect of a TiAu//Ni80Fe20(Py)/Bi2Se3/Al2O3 TI device. The SML arises from the Bi2Se3 (TI)’s surface state, where a unique coupling between current and spin-polarization occurs for the electrons within a few nanometers of the surface. Taking advantage of the unique device geometry and the x-ray setup, we are able to rotate the Py’s moment in presence of the SML effect. During Py moment rotation, we probe the (SOC) effect between the Py and TI surface state by the element-specificity of x-ray magnetic circular dichroism (XMCD). The setup allows us to control the spin polarization direction by changing the current direction within the device during the XMCD measurements. This enables a straightforward detection of the spin-orbital torque (SOT) exerted from the Py layer, as well as making an insightful view of the spin signal transferred mechanism at the TI surface state. This research may open many research opportunities in spintronic technology.

(a)Device structure for probing spin transferred mechanism at the topological insulator surface state. Blue arrow indicates the applied magnetic field direction. (b) (Left) Surface state dispersion of the bulk band gap of a topological insulator. (Right) Spin-momentum locking of the surface states (spin orientation indicated by red arrows) viewed in the k-space. (c)The interactions between the spins at the TI surface state and the aligned spin moment in the Py layer by spin-orbital coupling. The red arrows are the spin orientation, and the blue arrows are the aligned moment in Py layer.

B-274

PP-02

Inverse Spin Hall effect in cobalt thin films

Yi-Chien Weng,(a),(b) C-T. Liang(b), and J. G. Lin(a),*

(a)Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan

(b)Graduate Institute of Applied Physics, National Taiwan University, Taipei 10617, Taiwan

*Corresponding author: jglin@ntu.edu.tw

The ferromagnetic resonsnce (FMR) induced inverse spin Hall effect (ISHE) is

often studied in ferromagnet-normal metal (F-N) bilayer structures [1, 2]. In this work,

we investigate the ISHE in single F layer structures. A series of single layer thin films

of cobalt (Co) were prepared by a sputtering system with different working distances

and with the thickness being fixed as around 10 nm. The working distance from Co

target to substrate changes from 6.7 cm to 10.2 cm. The FMR induced ISHE

experiment were carried out at room temperature. The results show that the thin film

made with distance of 10.2 cm has a smallest FMR linewidth of 94 Oe, and a largest

ISHE voltage of -10.5 V at 100 mV microwave power. The causes for the variation of

ISHE voltage with changing the working distance will be discussed.

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Fig. 1 ISHE voltage for cobalt thin films with different working distance.

[1] F. D. Czeschka et al., PRL 107, 046601 (2010)

[2] J.-C. Rojas-Sánchez et al., PRL 112, 106602 (2014)

B-275

PP-03

Tuning the Schottky barrier of two-dimensional lateral

heterostructure by strain engineering

Hwihyeon Hwang, Jaekwang Lee*

Department of Physics, Pusan National University, Busan, 46241, Republic of Korea

e-mail: jaekwangl@pusan.ac.kr

It has been know that Schottky barrier (SB) formed at Metal-semiconductor junction

is one of the very important key parameters determining modern electronic device

performance and efficiency.

Recently, two-dimensional (2D) transition metal dichalcogenides have emerged

among the hottest classes of materials owing to their promising properties for future

applications. Compared with their bulk counterparts, 2D materials can sustain much

higher elastic strain up to 10 %.

Here, using density functional theory, we find that the SB height (formed at

semiconducting MoS2 and ferromagnetic metal VS2) is spin dependent and tunable by

about 0.1 eV due to the uniaxial strain.

We expect these strained lateral heterostructures can be a promising 2D-based

rectifying device such as transistor, diode and spintronics.

B-276

PP-04

Effect on Defect in Mn-doped Ferromagnetic AlGaP2 Semiconductor

Byung-Sub Kang(a), Kie-Moon Song(a), Kyeong-Sup Kim(b), Seong-Cho Yu(b), and Haeng-Ki Lee(c)

(a)Nanotechnology Research Centre, Dept. of Nano science and Mechanical

engineering, Konkuk University, Chungju, 27478, South Korea (b)Dept. of Physics, Chungbuk National University, Cheongju, 28644, South Korea

(c)Dept. of Radiotechnology, Suseong College, Daegu, 42078, South Korea e-mail: kangbs@kku.ac.kr,kmsong@kku.ac.kr

The AlGaP ternary material is used in devices such as visible light-emitting diodes, laser diodes, heterojuction bipolar transistors, and so on [1]. The opportunities of spintronics applications have limited due to the low solubility of magnetic ions in non-magnetic semiconductor hosts. Diluted Magnetic Semiconductor (DMS) possess interesting magnetic behaviour arising due to the replacement of small amount of host anion by magnetic impurity. For the realization of DMS materials in practical applications, they should exhibit room temperature ferromagnetic ordering. When ferromagnetic metals are used as spin injectors, the polarization in the semiconductor tends to be quickly lost via spin-flip scattering. It is one of the primary challenges to create the ferromagnetic semiconductors due to the difficulty in the spin-injection into the semiconductors to form DMS at room temperature.

In the present work, we studied by using first-principle calculations for the electronic and magnetic properties of (Mn,Al)-codoped to fabricate GaP-based DMS. In Mn-doped AlGaP2

chalcopyrite semiconductor, we observed the electronic properties, showing that both electrons and holes are capable of inducing ferromagnetism in this material. Total energy calculations predicted that the ternary compound AlGaP2 is direct semiconductor with band gaps (1.23eV). The calculated magnetic moment is 3.6~4.1μB/Mn (Fig.1). The ferromagnetism arises from two distinguishing characteristics by polarons and by holes-mediated exchange-coupling. We noted that this chalcopyrite and related materials can replace the Mn-doped III-V systems and open the way to room temperature spintronic devices.

[1] M.E. Overberg, and co-workers, J. Vac. Sci. Technol. B 21(5), 2093 (2003).

Fig.1. Mn magnetic moments.

B-277

PP-05

Study of domain-wall motion by IrMn/CoFeB exchange bias in a magnetic wire

Deng-Shiang Shiu (a), Chi-Yang Lin (b)

(a)Department of Physics, University of A, A-City, Taichung, Taiwan (b)School of Engineering, University of B, B-Town, 222, Republic of B

e-mail: author@a-univ. ac.jp

As the magnetic information bits move by magnetic domain walls (DW) be faster. In this study the DWs is vortex DW(VDW). VDWs also can be bits for logic control . It is important to control and read VDWs in magnetic-wire. We employed the exchange bias to control the DWs moving. We employed a method of exchange bias to pin the domain wall in a magnetic wire. Using crossed antiferromagnetic (AF) bars and ferromagnetic (F) wire induce the exchange bias to pin the domain wall . The structure at crossing point is Ta(20 nm)/NiFe(6 nm)/IrMn(10nm)/CoFeB(7 nm)/Ta(20 nm). The AF bars we design four widths of 1 μm, 1.5 μm, 2μm and 2.5 μm, to determine the pinning field and we obtain fields of 16.76, 19.76 and 21.31 Oe in different AF bars, respectively.

In order to examine the pinning field, we will utilize asymmetry pad to decrease the injection field. That applied the smaller field to injected DW into wire. The experiment device was fabricated by lift-off and magnetron-sputtering. DW measured by MOKE-microscope or MFM to obtain the pinned field. We will run the micromagnetic simulation to determine the structure of DWs and use the exchange bias assist switch the polarity of vortex.

[1] I. Polenciuc, A. J. Vick, D. A. Allwood, T. J. Hayward, G. Vallejo-Fernandez, K. O’Grady, and A. Hirohata Appl. Phys. Lett. 102.162406 (2014)

B-278

PP-06

The Spin Electron Moves on Line Defect in Honeycomb Structure

Tsung-Wei Huang(a)* and Ching-Ray Chang(a),(b)† (a)Department of Physics, National Taiwan University, Taipei 10617, Taiwan

(b)Graduate Institute of Applied Physics, National Taiwan University, Taipei s10617, Taiwan

e-mail: *d98222019@ntu.edu.tw and †crchang@phys.ntu.edu.tw Recently, two-dimensional honeycomb lattice such as silicene, geremanen and graphene [1]

have enormous application potential. They have different intrinsic spin-orbital interaction. For example, graphene has extreme low intrinsic spin-orbital interaction so graphene has long spin diffusion lengths at room temperatures. And the other hand, the electron transports along the line defect in graphene system. Hence we focus on the spin separated and propagation along the line defects by inducing spin orbital coupling controlling by the gate votage.

Using non-equilibrium Green function (NEGF) theory [2][3], we study the electron and spin transport behaviors in zigzag honeycomb nanoribbon with 3 line defects which are parallel [4][5] with zigzag edge. The hopping energy just considered the nearest neighbor hopping t, low bias 0.0001t and the spin orbital-coupling(SOC) for control the spin current. In charge density simulation, we find that although electron will be still blocked by the defect perpendicular with zigzag edge, however, the tunneling electron trapped in the zigzag edge and the defect parallel with zigzag edge. Moreover, in spin density simulation, the spin up electron accumulated on one-line defect and spin down on another.

[1] Garcia, J. C.; de Lima, D. B.; Assali, L. V. C.; Justo, J. F. (2011). "Group IV graphene- and graphane-like nanosheets". J. Phys. Chem. C 115: 13242.

[2] Supriyo Datta. "Electron transport in mesoscopic system". Cambridge

University Press, Cambridge (1995).

[3] D. K. Ferry and S. M. Goodnick, Transport in Nanostructures (Cambridge,

UK, 1997)

[4] Jayeeta Lahiri, You Lin, Pinar Bozkurt, Ivan I. Oleynik and Matthias Batzill

"An extended defect in graphene as a metallic wire" NATURE

NANOTECHNOLOGY | VOL 5 | MAY 2010

[5] Juntao Song, Haiwen Liu, Hua Jiang, Qing-feng Sun, and X. C. Xie

"One-dimensional quantum channel in a graphene line defect" Phys. Rev. B 86,

085437(2012)

Fig. 1 The structure of the line defect and honeycomb

lattice, (a1) the band structure for the perfect

honeycomb lattice with zigzag edge. (a2) the band

structure for a line defect in honeycomb lattice there is a

new flat band at fermi energy. (a3) the charge density of

the honeycomb lattice with a line defect

Fig. 2. The purple shadow is mark for line defects. Considering two

semi-infinity leads, which are zigzag honeycomb structure with line defect

parallel with zigzag, contact to left and right side of sample. Consider the

nearest neighbor hopping energy t, low bias 0.0001t, and all of the sample

SOC 0.2t.The left picture shows the electron density, and large ball means

large density. The right picture shows the spin density in out of the plane

direction, z direction. The red ball is spin up and blue is spin down also the

large ball means large density. It is easy to see spin up accumulated at upper

line defect, and spin down at bottom line defect.

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PP-07

Variations of the Kerr Signals of the NiFe/ZnO Bilayers Under Voltage Modulations

Zheng-Wei Lin, Chin-Chung Yu, Hsin-Hua Ko

Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan

e-mail: sturtle1992@gmail.com

The magnetic states of traditional spin electronic devices usually controlled by magnetic fields or small currents. In such devices, the thermal stability must be well controlled. To overcome the thermal disaster, voltage-control magnetic devices composed of a ferroelectric/ferromagnetic bilayer have been developed.

In this study, permalloy films with 80 at% of Ni were fabricated on ZnO(0001)/highly doped N-type Si(001). The longitudinal Kerr signals of the NiFe were measured as the ZnO(0001) layer subject to an electrical voltage with different values and periods. We found that Kerr signals can be well modulated as the value(/ period) of the voltage higher than 4V(/ 1s). And the drop of the signal was getting larger as elevating (/ prolonging) the applied voltage (/ period). As pointed by previous reports, the modulation of the Kerr signals was resulted by the strain coupling between the permalloy film and the ZnO piezoelectric layers. The drop of the Kerr signal, proportional to the applied voltage, can be explained as the lattice distortion of the permalloy film resulted by the nearby ZnO lattice. As the ZnO layer subjected to a voltage, the Kerr signal dropped firstly follow the charging behaviour of a capacitor. Figure 1 showed the modulation of the Kerr signals under a voltage of 9V with a period of 10s. Moreover, the signal increased monotonically as the time larger than 15s. It is possibly due to the thermal effect in the ZnO layer resulted by the small emission current. Such a thermal effect can release the lattice strain in the ZnO layer. To maintain the Kerr signal under a voltage will be a key issue from the application point of view.

Fig.1 Fig.2

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PP-08

Fabrication and Characterization of Fully-Epitaxial Superconductor/Half-Metallic Heulser Alloy Films

I. Shigeta(a), T. Kubota(b), K. Makise(c), S. Kimura(b), S. Awaji(b), B. Shinozaki(d), K. Koyama(a), K. Takanashi(b), M. Hiroi(a)

(a)Grad. School of Sci. & Eng., Kagoshima University, Kagoshima 890-0065, Japan (b)Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

(c)National Institute of Informa. & Communi. Tech., Hyogo 651-2492, Japan (d)Department of Physics, Kyushu University, Fukuoka 812-8581, Japan

e-mail: shigeta@sci.kagoshima-u.ac.jp

Heusler alloys have attracted a lot of interest as suitable materials for spintronic applications. With regards to Co-based Heusler alloy Co2FexMn1−xSi (CFMS), giant magnetoresistive devices experimentally gave high magnetoresistance ratio. On the other hand, superconducting NbN is a type-II superconductor, and its superconducting transition temperature Tc and upper critical field Hc2 are higher than other metallic superconductors. NbN is used for superconducting Josephson devices realizing high speed and low electricity consumption. The establishment of fabrication process and characterization of fully-epitaxial NbN/CMFS films is important for the applications of novel spintronic devices combining superconductor to half-metallic material.

We have prepared fully-epitaxial NbN/CFMS films on a MgO(100) substrate by an ultrahigh-vacuum (UHV)-compatible magnetron sputtering system. Fig. 1 shows temperature dependence of resistivity ρ of NbN/CFMS films with several different CFMS thickness. The Tc depended on the CFMS thickness. The magnetization curves were also measured for NbN/CFMS films at 300 K. Fig. 2 shows the magnetization curves in the (100)- and (110)-directions of the CFMS film. The magnetic anisotropy was observed and easy axis of magnetization is along the (110)-direction. The saturation magnetization Ms of the NbN/CFMS film was 872 emu/cc, which is similar value to bulk CFMS samples. Therefore, we were successful to fabricate fully-epitaxial NbN/CFMS films for the applications of spin spintronic devices.

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NbN(15nm)/CFMS(1nm)NbN(15nm)/CFMS(3nm)NbN(15nm)/CFMS(5nm) Tc=12.3 K

Fig. 1 Temperature dependence of the

resistivity of the NbN/CFMS films.

-2000 -1000 0 1000 2000-1000

-500

0

500

1000

M (

emu

/cc)

H (Oe)

CFMS(100)-direction CFMS(110)-direction

NbN(15nm)/CFMS(5nm)

Fig. 2 Magnetization curve of the

NbN/CFMS film at 300 K.

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Strain induced modulations of the Kerr signal and coercivity of the NiFe films

Chin-Chung Yu, Hsin-Hua Ko, Zheng-Wei Lin

Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan

e-mail: yucc@nuk.edu.tw

The magnetic states of traditional spin electronic devices usually control by a magnetic field or a small current. In such devices, the performance, signal-to-noise ratio and dimension are strongly influenced by their thermal stability. To overcome the thermal disaster, the magnetic devices through voltage controls have been developed. One of the successful methods is to manipulate the magnetic state through the strain provided from a ferroelectric (/ piezoelectric) material. In this study, the permalloy films with thicknesses, t, equal to 10 and 50nm were fabricated on ZnO(0001) layers. The MOKE signals and hysteresis loops of the NiFe films were measured while the ZnO(0001) layer was subject to an electrical potential.

The piezoelectric constant d33 and coercivity of the ZnO(0001) film was characterized by a PFM and has values of 5.0 pm/V and 0.2V, respectively. And after 1V, the saturated state was reached. The threshold voltage for the reduction of coercivity (Hc) is 2.2V and 5.1V for t= 10 and 50nm, respectively. And a monotonic reduction of the Hc and Kerr signal of the NiFe films was observed no matter what polarity of the electric field was. The reduction ratio of the Hc and Kerr signal were 64% and 0.5mV (/ 43% and 0.4mV) for the 10nm- (/ 50nm-) thick sample after applying 10V across the ZnO layer. It is clear that the strain field stored in the NiFe layer fade away as t getting larger. The Hc and Kerr signal can be manipulate repeatedly under a potential below 10V. As the potential higher than 11V, nonlinear Kerr signals were observed. At the same time, the ZnO layer displayed a strong leakage current. Under an operation of the step potential between 0V and 10V, a delay of the response of Kerr signal can be observed. The dynamic behaviour of the delivery of the strain field between ferromagnetic and ferroelectric layers will be discussed.

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Fig. 1: Bi2Se3 with surfacein y direction

Fig. 2: In-plane spin texture of Bi2Se3 with surface in (a) z and (b) y direction.

Spin texture changes in different surfaces of topological insulator Bi2Se3

Ming-Chien Hsu(a), Heui-Ru Fuh(b), Ke-Chuan Weng(c), Yeu-Chung Lin(b) and Ching-Ray Chang (b)

(a)Department of Electrical and Computer Engineering, National University of Singapore, Singapore

(b)Department of Physics, National Taiwan University, Taiwan (c)Research Center for Applied Sciences, Academia Sinica, Taiwan

e-mail: crchang@phys.ntu.edu.tw

Spin utilization and manipulation plays a key role in spintronics and magnetic devices. Systems with intrinsic spin property provide platforms of spin control. One prominent example is the topological insulator (TI) which has a nontrivial topological Z2 invariant inherited in the bulk system. Due to the bulk-edge correspondence, the TI with boundary surface has surface states whose spin has preferred direction that exhibits the great advantage to be utilized in the spintronics devices. It was experimentally confirmed that the famous three-dimensional TI Bi2Se3 stacking in the (111) z direction has surface states whose spin is locked perpendicular to the momentum direction. However, this does not fully utilize the potential to manipulate the spin in TI. Actually, the bulk-edge correspondence allows different spin textures in surface states localized in different boundary surfaces. Using the ab initio calculation, we demonstrated that the spin indeed has only one allowed direction (either parallel or antiparallel) near the Γ point in Bi2Se3 cut in surface perpendicular to (111) direction, different from the observed spin circulation around

the Γ point in (111) cut Bi2Se3. The different spin texture in different surface orientation was theoretically demonstrated in the first-order continuum model [1] and was confirmed in our full ab initio calculation. Constructing the tight binding model from finite differencing the continuum model up to third order, we also confirmed the changes in spin textures in different cut surfaces from the same bulk Hamiltonian. The

localization of these surface states was also confirmed. The different spin textures resulting from different surfaces can be utilized in spin manipulation and controls in devices. [1] F. Zhang, C. L. Kane, and E. J. Mele, Physical Review B 86, 081303 (2012).

(a)

(b)

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Perpendicular magnetic anisotropy of Non-magnetic Materials/Ferromagnetic Materials/MgO trilayer

In Ho Cha(a), Yong Jin Kim(a), Gyu Won Kim(a), Young Keun Kim(a)

(a)Department of Materials Science and Engineering, Korea University, Seoul 02841 Korea

e-mail: ykim97@korea.ac.kr

Spin-Orbit Torque Magnetic Random Access Memory (SOT-MRAM) with perpendicular magnetic anisotropy (PMA) materials have received greater interest because of their advantages such as low magnetization switching current and fast switching time. Recent studies reported spin-orbit torque in NM/FM/MgO structure with PMA using various non-magnetic materials (Ta, W, Pt, etc.) and ferromagnetic materials (CoFeB, Co, etc.) [1], [2], [3].

In this study, we investigated the magnetic properties of NM/FM/MgO structure using various NM and FM. The sample were deposited by dc and rf magnetron sputtering under the base pressure below 5x10-9 Torr. Each sample went through post-annealing at 300oC for 1 hour in a magnetic field of 6 kOe under 1x10-6 Torr. The magnetic properties were measured using a vibrating sample magnetometer (VSM). [1] Q. Hao and G. Xiao, Physical Review B, 91, 224413 (2015). [2] C. H. Sim, J. C. Huang, M. Tran and K. Eason, Applied Physics Letters, 104, 012408 (2014) [3] S. Cho, S. C. Baek, K. Lee, Y. Jo and B. Park, Scientific Reports, 5, 14668 (2015)

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Influence of Magnetic Structures on the High-frequency Characteristics of Bilayer Composite Structures

W. C. Tang(a), Z. W. Fan(b), Y. G. Yang(b), H. T. Huang(a), and Z. Wei(a)

(a)Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan

(b)Regional R&D Services Department, Metal Industries Research and Development Centre, Taichung 407, Taiwan

e-mail: vfande245@hotmail.com This study discusses the influence of patterned magnetic films on the changes of ferromagnetic

resonance curves in bilayer composite structures. Magnetic elliptical array was prepared on Permalloy (Ni80Fe20, Py) or Co continuous film forms a bilayer composite structures. Owing to the different exchange lengths in each material, magnetic thin films have different sizes of magnetic domains, which may affect the exchange coupling interaction between the magnetic structure and the magnetic continuous film. For the case with Substrate/30 nm Co continuous film/30 nm Py elliptical array, Py elliptical array can easily vary the ferromagnetic resonance property of composite structures and the direction of magnetic field also affect resonance property, as shown in Fig. 1(a)(b). In contrast with the case of Substrate/30 nm Py continuous film/30 nm Co elliptical array, Co elliptical array cannot affect the ferromagnetic resonance property of composite structures and the signal of Py film disappears regardless of the direction of magnetic field, , as shown in Fig. 2(a)(b).

Fig. 1. Ferromagnetic resonance curves for 30 nm Co film, 30 nm Py film, 30 nm Py elliptical array, and Sub./30 nm Co film/30 nm Py elliptical array. (a) The magnetic field is parallel to the major axis of the ellipse (H//). (b) The magnetic field is perpendicular to the major axis of the ellipse (H⊥).

Fig. 2. FMR curves for 30 nm Co film, 30 nm Py film, 30 nm Co elliptical array, and Sub./30 nm Py film/30 nm Co elliptical array. (a) The magnetic field is parallel (H//) to the major axis of the ellipse. (b) The magnetic field is perpendicular (H⊥) to the major axis of the ellipse.

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100 nm

(a-1) (a-2) 1000 cycles

(b-1) (b-2) 3000 cycles

5

10

15

20

25

30

Res

olut

ion

(nm

)

0 1000 2000 3000Number of scan cycle

(no layer)

C layer

Si-N layer

Fig. 1 MFM images of magnetic recording (500 kFCI) observed by using tips without (a) and with 2 nm thick carbon layer (b).

Fig. 2 Effects of 2 nm thick protection layer on MFM resolution.

Durability Improvement of High-Resolution MFM Tips

Masaaki Futamoto, Kei Kato, Yuma Tomita, Mitsuru Ohtake

Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan e-mail: futamoto@elect.chuo-u.ac.jp

Observation of magnetization structure by magnetic force microscopy (MFM) has

been playing important roles in the development of magnetic materials and devices. MFM tips are prepared by coating magnetic materials on sharp non-magnetic tips like Si and SiN [1]. However, the magnetic materials are easily oxidized when kept under ambient atmosphere. Furthermore, MFM tips will be easily deformed upon contact with observation samples, since the magnetic materials are far softer than the base tip of Si or SiN. The high resolution property will deteriorate when oxidation or deformation takes place. In order to enhance the durability of high-resolution MFM tip, very thin protection layers are applied on MFM tips and the effects on oxidation and mechanical durability are investigated.

Fig. 1 compares the MFM image

obtained by using tips with and without 2-nm thick carbon protection layer before and after contact scanning, where the tips were prepared by coating 20 nm thick Fe on Si base-tips of 4 nm top radius. The MFM contrasts from 50 nm bit length (500 kFCI) are lost after 1000 times of 2 m scan cycles on a 　disk-media sample with applying a load of 3 x 10-7 N for a tip without protection layer, whereas clear images are kept even after 3000 times of scan for the tip with 2 nm thick carbon layer. The results of mechanical durability for C and Si-N coated MFM tips are summarized in Fig. 2. The effects on oxidation will also be discussed at the conference. The present study has shown that application of very thin protection layer of hard and dense material enhances greatly the mechanical and chemical durability of high-resolution MFM tip. [1] M. Futamoto and M. Ohtake; Key Eng. Mater., 644, pp.189-195 (2015).

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Sensitivity of a Fluxgate Sensor Using Magnetic-Domain-Controlled Amorphous Core

H. Miyata(a), R. Yamamoto(b), Y. Morimoto(b), M. Takezawa(b)

(a) MTI Co., Ltd., Kitakyushu, Japan (b) Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu, Japan

e-mail: miyata@mticorp.co.jp

Previously, we reported that the output of a fluxgate sensor depends on the magnetic domain structure of the core materials [1]. Therefore, to ensure low noise and high sensitivity of the sensor, the domain change applying the AC magnetic field must be repeatable. In this study, the jitter noise was reduced by cutting an amorphous ribbon at its edge prior to annealing. The resulting domain structure of the amorphous core was observed by using a Kerr microscope. The relationship between the noise in the fluxgate sensors and the repeatability of the domain change was examined.

Figure 1 shows the dynamic magnetic domain images obtained by applying an AC field of ±9 Oe at 4 kHz to the uncut Co–Fe–Ni–Si–B amorphous ribbons. The change in the domain image was extracted by subtracting a reference image collected under an AC applied field. The subtraction was performed by an image processor. Adjacent regions of dark and light contrast indicate the sites of wall displacement. Wall displacement of a few tens of microns was observed. However, the distances and positions of the wall displacements differ between the first and second observations. Therefore, the magnetization process has no repeatability and causes jitter during the magnetization reversal.

In Fig. 2, the ribbon was cut at its edge and annealed at 300 °C for 3 h in a DC field of 200 Oe. The cutting angle was 60°. The wall displacement is now consistent between the first and second domain observations. The acute angle shape of the ribbon end nucleates the reversal domain at the same site in each cycle of the magnetization process. However, the domain-controlled amorphous core does not decrease the noise in the fluxgate sensor. Apparently, the jitter at the ribbon end exerts much less effect than the output of the 20-mm-long sensor. Nonetheless, the domain-controlled amorphous core reduces the magnetization reversal jitter.

[1] H. Miyata, et al., IEEE Trans. Magn., 50, 4005804 (2014).

Fig. 1. Dynamic magnetic domain images of amorphous ribbon:

(a) first and (b) second observations.

Fig. 2. Dynamic magnetic domain images of amorphous ribbon cut at its edge: (a) first and (b) second observations.

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Fabrication and Dispersion of Fe3O4 Nanopowder using Co-Precipitation Method for Magnetic Fluid

Preparation.

Jung-Kab Park, Seung-Bin Baeg, Yung-Il Song, Su-Jeong Suh

School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea

e-mail: godory2505@skku.edu

A magnetic fluid comprises magnetic particles, a surfactant, and a base fluid. Magnetic particles (Fe3O4) are approximately 10 nm in size, and being repulsive, do not precipitate and are evenly dispersed in the base fluid by the surfactant. When a magnetic field is applied, the magnetic particles powder is arranged along the magnetic lines of force, and again disperses uniformly when the magnetic field is removed, thus exhibiting the property of superparamagnetism. In other words, when ferromagnetic powder becomes nano-sized, it gains the property of superparamagnetism by the size effect. Therefore, magnetic fluid is applied to various fields such as speakers, dampers, and vacuum seals.

In this study, magnetite powder is produced using the co-precipitation method. First FeCl2·4H2O (3.97 g, 0.02 mol) and FeCl3·6H2O (5 g) are dissolved in 50 mL DI while stirring at 500 rpm for 30 minutes. Next, 2M NH4OH aqueous solution is added dropwise, at a rate of 5 mL per minute. The color of the solution slowly turns from brown to black, and magnetite particles are formed. The powder is then washed 10 times by distilled water and is desiccated at 80 for 10 hours in an atmosphere of N2. The desiccated powder is altered with its concentration by using a fluorinate surfactant and is dispersed by ultrasonic waves for 3 hours. By using ethanol and distilled water, the powder is washed and desiccated at 80 for 10 hours in vacuum. The powder is then pulverized and dispersed by the ball mill process with silicone oil, in order to prepare the magnetic fluid.

The saturation magnetization value of the powder was measured as 79 emu/g, by using a vibration sample magnetometer (VSM). XRD was used to confirm the crystalline property of the magnetite. The average particle size of the powder was determined as 12 nm by using TEM. The magnetic fluid fabricated by the ball mill process had the shape of a spike, as was confirmed by applying a magnetic field.

[1] . Bing Tang, Liangjun Yuan, Taihong Shi, Linfeng Yu, (2009) 1173–1178

10.68 n

m

11.36 nm

Spike

Ball M

Fig. Fabrication of magnetic fluid using Fe3O4 nanoparticles

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Magnetically Barcoded Microcarriers Detection with TMR sensors Pratap Kollu, Adrian Ionescu,

David M. Love, C. Cimorra, Justin Llandro and C.H.W. Barnes

Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK Email:pk419@cam.ac.uk, web site: http://www.tfm.phy.cam.ac.uk/

We are working towards a novel lab-on-a-chip technology based on suspended magnetically encoded

microcarriers [1,2]. Our newest generation of microcarriers consist of up to fourteen individual magnetic

elements encapsulated within a SU8 polymer and gold layer (Fig. 1.b), which both provide routes to

bio-functionalization through surface epoxide groups and thiol chemistry [3]. The writing/reading of the

digital magnetic codes is obtained through coercivity engineered magnetic elements (Fig. 1.a), while the

detection is performed by means of a tunneling magneto-resistance (TMR) sensor. The global address-ability

of these bits is achieved by utilizing magnetic shape anisotropy. The possibility of attaching different

fluorescent labels to each side of the microcarriers enables a positive control in binding assays. Potential

applications for this platform range from DNA/protein analysis for genotyping and point-of-care diagnostics to

drug development and combinatorial chemistry.

Alternative magnetic detection platforms include asymmetric giant mageto-impedance (GMI) thin film

sensor [4,5], which possess a high sensitivity and are currently under development. Films are deposited at

room temperature using dc magnetron sputtering. Test sensor are patterned by UV photo-lithography and

lift-off processes to form strips 0.2 mm wide and 10 mm long on glass/silicon wafers. The films consist of a

symmetrical multilayer structure of the following composition: Ti(10 nm)/NiFe(5 nm)/IrMn(15 nm)/NiFe(40

nm)/Cu(100 nm)/NiFe(40 nm)/IrMn(15 nm)/NiFe(5 nm)/Ti(10 nm). The thin film structure gives a significant

GMI response as will discussed. Linear GMI behaviour can be obtained around zero external field by tuning

the frequency, without the need for external biasing fields or additional coils.

Fig1. a, Illustration of composite magnetic elements. b, Constituents of bi-functional microcarriers.

1. J. Llandro et al., Medical & Biological Engineering & Computing 48, 977 (2010).

2. B. Hong et al., in "Biomagnetism and Magnetic Biosystems Based on Molecular Recognition Processes",

edited by J.A.C. Bland and A. Ionescu, AIP Conf. Proc. 1025 (2008).

3. K.N. Vyas et al., Lab on a Chip 12, 5272 (2012). 4. C. Garcia et al., Applied Physics Letters 96, 232501 (2010).

5. S.S. Yoon, P. Kollu et al., IEEE Trans. Magn. 45, 2727(2009)

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Design Optimization of an SPM Motor With Minimized Usage of Rare-Earth Magnets

C. T. Liu(a), C. C. Hwang(b), C. J. Hong(c)

(a) Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung 804, Taiwan

(b) Department of Electrical Engineering, Feng Chia University, Taichung 407, Taiwan

(c) Ph.D. Program in Electrical and Communications Engineering, Feng Chia University, Taichung 407, Taiwan

e-mail: cchwang@fcu.edu.tw

This paper describes a two-step design optimization applied to the integral-slot windings surface-mounted permanent-magnet (SPM) machines. It is a three-phase, 4-pole, 36-slot, 3.7 kW, and 2000 rpm SPM motor, as shown in Fig. 1. Fig. 1. Winding layouts for one phase of (a) lap and (b) concentric windings. There are

two parallel paths in both windings with each turn formed 0.5 mm diameter wire. For (a), each coil has 41 turns as shown in (c). For (b) coil W has 21 turns, coils X and Y have 41 turns, coil W’ has 20 turns, and coil Z’ has 21 turns as shown in (d).

In the first-step optimization, a method that expresses the no-load flux linkage as a function integrated over the PM volume is used to identify the contribution of each PM volume element to generate a no-load flux linkage [1]. We apply it to optimize the magnet shape in the rotor by deleting the lower contribution elements. This can not only reduce the magnet usage but improve the machine performance. In the second-step optimization, the geometry of stator is considered, and the fuzzy-based Taguchi method coupled with finite element analysis (FEA) is employed to further enhance the machine performance. Experimental result shows that this technique can not only improve the machine performance but also reduce the use of magnets while still maintaining the required value of average torque. [1] C. C. Hwang, C. M. Chang, and C. T. Liu, IEEE Transaction on Magnetics, 49,

3925 (2013).

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Design of a Coaxially Magnetic-geared Linear Actuator for Electric Power Steering System Applications

Cheng-Tsung Liu(a), Chang-Chou Hwang(b), Yu-Wen Chiu(a)

(a)Dept. of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (b)Dept. of Electrical Engineering, Feng Chia University, Taichung, Taiwan

e-mail: ctliu@ieee.org

This paper will present the designs and feasibility assessments of a linear electromagnetic actuator for providing the required power steering forces directly [1]. A systematic scheme for designing the coaxially magnetic-geared linear actuator will be established and the specifications of electric power steering (EPS) system for an economy-sized vehicle will be adopted to the system structural designs. Within the physical and operational constraints, the device is coaxially composed by a tubular linear PM motor and a tubular magnetic gears set as conceptually shown in Fig. 1. Determinations of the optimized geometrical compositions of the motor and the gears set based on the fluxes and thrust forces that can be conveyed will be assessed in detail. By considering the vehicle operational speeds, the corresponding dynamic performances of the proposed EPS system, as illustrated in Fig. 2, and the resulting radii of turning circles are also evaluated. It is thus confirmed that the adoptions of such electromagnetic systems for those common EPS systems in the vehicles are technically feasible. [1] H. Akhondi and J. Milimonfared, Journal of Asian Electric Vehicles, 2, 1283 (2009).

Fig. 1 Conceptual structure of the coaxially magnetic-geared linear actuator.

(a)

(b)

Fig. 2 Flux density distributions and dynamic thrust force and position responses of the proposed EPS system at different vehicle speeds. (a) At 10 km/h, (b) At 120 km/h.

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Fundamental Analysis of a PMSM with High Flux Density Using FEM

K. Miyahara, R. Ishikawa and T. Yoshida

Department of Electrical Engineering, Kyushu University, Japan e-mail: miyahara@em.ees. kyushu-u.ac.jp

The use of permanent magnet (PM) motors for various applications is increasing due to their high performance. So far, we have studied a PM linear synchronous motor (LSM) with high flux density. By arranging the PMs so that the same poles face each other, the airgap flux density exceeds the value of the residual magnetic flux density of the PM. With this structure, high propulsion force density can be realized. This structure can be also applied to a rotational PMSM.

In this study, we first designed a PMSM with this structure for a direct-drive in-wheel motor, and then, explored its fundamental characteristics by using 2D finite element method (FEM).

Figure 1 shows a side view of the designed PMSM (24-pole 27-slot). As shown, outer rotor topology is adopted. The inner and outer diameters of the rotor are 293 and 344 mm, respectively. While, the inner and outer diameters of the stator are 206 and 292 mm, respectively. In the analysis, NdFeB PMs with residual magnetic flux density of 1.15 T and coercive force of 872 kA/m were used. For the case when the stack length of the stator iron core is 55 mm, the torque of 349 Nm can be achieved at 8.5 . It corresponds to 68.3 Nm/L in terms of torque density. Figure 2 represents an efficiency map of the designed PMSM. The designed PMSM achieves high efficiency even at the middle and low rotational speed regions.

Fig. 1 Designed PMSM Fig.2 Efficiency map

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Completely Accessible Self-controlled Electronics Wheelchairs Motor Driver to Stabilization of

Acceleration of Gravity

Shun-Yuan Wang, Savrina Tung Department of Electrical Engineering, National Taipei University of Technology,

Taiwan e-mail: sywang@ntut.edu.tw

Consider of the rapidly aging populations in present danger, in

order to contribute the accessible living environment for aging and disable people, with the completely self-controlled mobility regardless of the height difference, such as the stairs, the threshold, the gap. We now develop the electronics wheelchairs driver with parallel of the three-wheels plus one pair of aid-wheel. This study is to solve the problem of acceleration of gravity while the wheelchairs loaded. The main task is to keep the wheelchairs well balanced and stable.

Stabilization is the major issue while a rolling loaded objectives accelerated by the gravity. Now the electronic wheelchairs mostly are driven by track. The design of track indeed to offer a stabilized motion, however, it’s not space-constraint to fit the real world. Most citizens in Taiwan live in apartment with the limited swing space going up and down. In this study, the proposed wheelchairs with parallel tri-wheels plus one pair of aid pair of wheels to lift or descent the chair. The most challenge is to descent the chair with loaded. We have eliminated the problem by control the motors. While the loaded chair descent, the system will make it stabilized and balanced. Extensive computational power and accurate measurement of the voltages and currents, as well as accurate knowledge of the motor parameters are required.

PMSM, larger torque is produced for the RMS current compared other PM motor. Hereby, it can be benefit an immediate reduction in power losses, which is quite important for the device rely only on the batteries.

The system applied two PMSM supplied by two voltage inverters. The main problem of the mechanical coupling is induced by the non-linear wheel-stairs adhesion characteristic when it’s loaded varied. PMSM control mode requires more precise angle measurements. Hereby, position and speed estimators would be an effective solution to achieve the PMSM control and benefit from its advantages, without using mechanical sensors. The above electrical and magnetic equations are the initial concepts for the position and speed extraction occurs by the voltage and current measurement. [1] Changsung Sean Kim, Dol:10.1109/IFEEC.2013.6687493, IFEEC, 2013 1st International.

[2] S. Devaneyan, INCOCCI, 2010 international Conference on

[3] A. Gkountaras, C.Dinca; A.Giedymin;P.Birgel; U.Schaefer;S.Dieckerhoff, Dol:

10.1109/EPE.2014.6910931 ,EPE’14-ECCE Europe, 2014 16th Europe Conference on

Fig. 1. The design concept of the wheel chairs

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This paper proposed a tubular transverse flux permanent magnet linear machine with

the class distribution of the stator laminations group arrangement, due to the problem

of larger thrust force ripple in the machine, which has some merits higher force density

and better controllable characteristic etc. Firstly, the structure and operating principle

of tubular transverse flux permanent magnet linear machine was presented. Secondly,

the influence of the class distribution of the stator laminations group arrangement on

the motor performance is analyzed in detail. Special attention is paid to the Back-EMF,

cogging force and electromagnetic force etc. The paper investigates the influence of

different arrangements in transverse flux permanent magnet linear machine, including

theoretical analysis and numerical calculation. The results show that the thrust ripple

can be decreased by the class distribution of the stator laminations group arrangement

in transverse flux permanent magnet linear machine. References [1]Luo Honghao, Wu Jun, Chang Wensen. “Minimization of Cogging Force in Moving Magnet Type

PMBLDCLM, ”Proceedings of the CSEE， vol.27, no.6, pp.12-16, 2007. [2]Jibin Zou, Qian Wang, and Yongxiang Xu. “Influence of permanent magnet magnetization length on the

performance of a tubular transverse flux permanent magnet linear machine used for electromagnetic launch,” IEEE Transactions on Plasma Science, vol.39, no.1, pp.241-246, 2011.

[3]Zhao, Mei, Zou, Ji-ming, Xu, Yong-xiang, et al. “The Thrust Characteristic Investigation of Transverse Flux Tubular Linear Machine for Electromagnetic Launcher,” IEEE Transactions on Plasma Science, vol. 39, no.3, pp.925-930, 2011.

[4]Do Hyun Kang, Herbert Weh. “Design of an Integrated Propulsion, Guidance, and Levitation System by Magnetically Excited Transverse Flux Linear Motor,” IEEE Transactions on Energy Converters, vol.19, no.3, pp. 477-484, 2004.

[5]J.-H. Chang, D.-H. Kang, J.-Y. Lee, et al. “Development of transverse flux linear motor with permanent magnet excitation for direct drive applications ,” IEEE Transactions on Magnetics, vol.41, no.5, pp.1936-1939, 2005.

[6]Do-Kwan Hong, Byung-Chul Woo, Dae-Hyun Koo, et al. “Optimum Design of Transverse Flux Linear Motor for Weight Reduction and Improvement Thrust Force Using Response Surface Methodology,” IEEE Transactions on Magnetics, vol.44, no.11, pp.4317-4320, 2008.

[7]Li Peng. “Basic research on bidirectional cross linking transverse flux tubular linear permanent magnet synchronous motor,” Harbin: Harbin institute of technology, 2011.

[8]Kou Baoquan, Yang Guolong, Zhou Weizheng, Zhang He. “Bidirectional Crosslinking Transverse Flux Flat Type Permanent Magnet Linear Synchronous Motor,” Proceedings of the CSEE, vol.32, no.33, pp.75-82, 2012.

[9]Zou Ji-bin, Zhao Mei. “Development and Analysis of Tubular Transverse Flux Machine with Permanent Magnet Excitation,” IEEE Transactions on Industrial Electronics, vol.59, no.5, pp. 2198-2207, 2012.

[10] Zhao Mei, Zou Jiming, Xu Yongxiang, et al. “The thrust characteristic investigation of transverse flux tubular linear machine for electromagnetic launcher,” IEEE Transactions on Plasma Science, vol.39, no.3, pp.925-930, 2011.

[11] Vincenzo Delli Colli, Piergiacomo Cancelliere, and Fabrizio Marignetti, et al, “A Tubular-Generator Drive For Wave Energy Conversion, ” IEEE Trans. on Industrial Electronics, vol. 53, no.4, pp.1152-1159, Aug.2006.

Design and Reduction of Thrust Ripple in Transverse Flux Permanent Magnet Linear Machine

Mei Zhao(a)* (b) (c), Fujun Han(a), Yunliang Zhang(c), Huixia Liu(a), Jibin Zou(b) (a)Department of Information and Electrical Engineering, Ludong University, Yantai, 264025, CHINA

(b) Department of Electrical Engineering, Harbin Institute of Technology, Harbin, 150001, CHINA (c)Weihai Guangtai Airport Equipment CO., Limited,Weihai,264200,CHINA

Email: meipersonality@126.com

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A novel high-performance magnetic transmission (MT) for converting between rotary and rectilinear motion is proposed. The construction and operation principle of the proposed MT are described. The analytic computational formula for air-gap flux density is obtained. The electrical magnetic distribution of the MT is computed by FEM. The characteristics of the novel MT are analyzed and compared with traditional magnetic transmission without ferromagnetic pole-piece. The optimum shape of ferromagnetic pole-pieces is discovered. The experiments are implemented to evaluate the performance of the prototype MT. The maximum static force and torque of the novel MT are measured. The experimental result verifies the rationality of the structure of the MT. Compared with conventional magnetic gear rack, the static force and torque of the novel MT are improved greatly.

Fig.1: Schematic of proposed MT. Fig. 2. Magnetic field distribution at the action of PMs in the inner rotor and outer mover.

The research shows that the structure of proposed MT is reasonable. The torque and force densities of the proposed MT

are improved significantly thanks to a larger magnetic field coupling area by adding the ferromagnetic pole-pieces. Meanwhile, variable velocity ratios between the inner rotor and outer mover can be easily achieved by adjusting the ferromagnetic pole-pieces. This work was supported by the China Postdoctoral Science Foundation under Grant 2014M550260, by the National Natural Science Foundation of China under Grant 51307022, by the Natural Science foundation of Jiangsu Province under Grant BK20130611, and by ANSYS, Inc.

REFERENCES 1. Kikuchi S, Tsurumoto K. Design and characteristics of a new magnetic worm gear using permanent

magnet[J]. IEEE Transactions on Magnetics, 1993, 29(6): 2923-2925. 2. Atallah Kais, and David Howe. "A novel high-performance magnetic gear," IEEE Trans. on Magnetics,

vol.37, no.4, pp.2844-2846, 2001. 3. Atallah Kais, J. Wang, and D. Howe. "A high-performance linear magnetic gear," Journal of Applied

Physics,vol.97, no. 10: 10N516.2005. 4. K. Atallah, S. D. Calverley, D. Howe. Design, analysis and realization of a high performance magnetic

gear[C]. IEEE Proceedings on Electric Power Applications, 2004, 151(2): 135-143. 5. Rasmussen P O，Andersen T O，Jorgensen F T，et al. Development of a high-performance magnetic

gear[J].IEEE Transactions on Industry Applications，2005，41(3):764-770. 6. Uppalapati K K, Bird J Z, Jia D, et al. Performance of a magnetic gear using ferrite magnets for low speed

ocean power generation[C]. Energy Conversion Congress and Exposition (ECCE), 2012: 3348-3355. 7. Bomela W, Bird J Z, Acharya V M. The performance of a transverse flux magnetic gear[J]. IEEE

Transactions on Magnetics, 2014, 50(1): 4000104.

Design and Analysis of Magnetic Transmission for Converting

Between Rotary and Rectilinear Motion

Xinghe Fu*, Biao Wang, Kai Liu, Mingyao Lin School of Electrical Engineering, Southeast University, Nanjing, China

fuxinghe@seu.edu.cn

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PQ-12

A novel transverse flux switched-flux linear motor (TFSFLM) is proposed in this paper, which has high thrust force density and low cost due to combining the advantages of transverse flux structure and switched-flux structure. Firstly, the structure and operating principle of TFSFLM was presented. Secondly, the magnetic field of a TFSFLM with one phase is numerically computed by three-dimensional (3-D) finite element method (FEM). Finally, the electromagnetic characteristics of the motor, including back-EMF and flux waveforms of winding and cogging force are numerically analyzed.

Fig. 1. The structure diagram of TFSFLM. Fig. 2. 3-D mesh plot in half single phase of TFSFLM.

In this paper, the transverse flux switched-flux linear motor (TFSFLM) with high force density and low cost is proposed in this paper. The magnetic circuit of this model is different in compared to the conventional three phase linear motor because it has separation magnetic circuit as each phase can produce thrust force. The novel structure and work principle are indicated by analysis of magnetic field. The winding flux linkage, back-EMF and cogging force are calculated by 3-D FEM.

References

1. I. Boldea, Syed A. Nasar. “Linear Electric Actuators and Generators,” Cambridge University Press, 2005. 91-232.

2. M. S. Hosseini, and S. V. Zadeh. Modeling and analysis of linear synchronous motors in high-speed maglev vehicles [J]. IEEE Trans. Magnetics, 2010, 46(7): 2656–2664.

3. Ping Zheng, Chengde Tong, Gang Chen, et al. Research on the Magnetic Characteristic of a Novel Transverse-Flux PM Linear Machine Used for Free-Piston Energy Converter [J]. IEEE Transactions on Magnetics, 2011, 47(5): 1082-1085.

Magnetic Field Analysis of a Novel Transverse Flux Switched-flux Permanent Magnet Linear Motor

Mei Zhao(a)* (b) (c), Yunliang Zhang(c), Fujun Han(a), Huixia Liu(a), Jibin Zou(b) (a)Department of Information and Electrical Engineering, Ludong University, Yantai, 264025,

CHINA (b) Department of Electrical Engineering, Harbin Institute of Technology, Harbin, 150001,

CHINA (c)Weihai Guangtai Airport Equipment CO., Limited,Weihai,264200,CHINA

Email: meipersonality@126.com

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Miniaturization of Implantable Micro-robot Propulsion using Wireless Power Transfer System

D. Kim(a), K. Hwang(a), J. Park(a), H.H Park(b), and S. Ahn(a)

(a)The CCS GSGT Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea

(b)Department of Electronic Engineering, The University of Suwon, Hwaseong, Republic of Korea

e-mail: dwkim88@kaist.ac.kr Recently implantable micro-robots have been researched actively in the means of

medical application. This micro-robot can be used for localized delivery and various forms of energy. Targeted drug delivery increases the concentration of drug in region of interest and reduce the risk of side effects in the rest of the body. In addition, the micro-robot can delivery heat energy to destroy unwanted cells and collect the images inside of the body to make an accurate diagnosis. Currently, most of research are use static magnet inside of micro-robot to generate propulsion force. This kinds of micro-robot can be implemented as nano-size, but the utilization of these are limited because of the it is not containing electrical energy source [1]. To receive the electrical energy, the micro robot using wireless power transfer system have been proposed. Unlikely conventional research which using motor actuator, generate propulsion using Lorentz force is pronounced [2].

In this paper, the concept of minimizing micro-robot using wireless power transfer which is generating propulsion force using Lorentz force between source coil and load coil has been proposed. Due to its extreme miniature size, there are additional considering factors about the micro-robot. For instance, the induced current flows in the load coil becoming lower because of the coupling coefficient of source coil and load coil are decreased. To compensate this phenomenon, the frequency of wireless power transfer system need to be increase as shown in Fig. 1.

Another issue of minimal micro-robot is design of coil structure. Though the size of micro-robot is same, the propulsion force and torque is different depends on the topology of micro-robot load coil structure.

[1] K. B. Yesin, K. Vollmers and B. J. Nelson,

“Modeling and control of untethered biomicrorobots in a fluidic environment using electromagnetic fields,” The International Journal of Robotics Research, vol. 25, pp. 527-536, February 2007. [2] D. Kim, J. Park, H.H Park, and S. Ahn,

"Generation of Magnetic Propulsion Force and Torque for Microrobot Using Wireless Power Transfer Coil," IEEE Transactions on Magnetics, Vol. 51, No. 11, Nov. 2015.

Fig. 1. Propulsion force and velocity depending various size.

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PQ-14

Application of SynRM Driving CVT System Using Blend Recurrent Gegenbauer OPNNAPSO Control

Chih-Hong Lin Department of Electrical Engineering, National United University, Miaoli, Taiwan

e-mail: jhlin@nuu,edu.tw In order to reduce effect of nonlinear time-varying uncertainty for a continuously variable

transmission (CVT) system driven by synchronous reluctance motor (SynRM), a blend recurrent Gegenbauer orthogonal polynomials neural network adaptive particle swarm optimization (OPNNAPSO) control system is proposed in this paper. The blend recurrent Gegenbauer OPNNAPSO control system consists of a censor control, a recurrent Gegenbauer OPNN control with adaptive law based on Lyapunov stability and a recompensed control. Furthermore, the adaptive particle swarm optimization (APSO) is proposed for regulating two varied learning rates of parameters in the recurrent Gegenbauer OPNN to obtain better dynamic response and faster convergence. Finally, comparative studies demonstrated by experimental results are illustrated to verify the effectiveness of the proposed control scheme.

Fig. 1. The CVT system. Fig. 2. Block diagram of the SynRM driving CVT.

The blend recurrent Gegenbauer OPNNAPSO control system has been successfully developed

for controlling the SynRM driving CVT system with robust control characteristics. Firstly, the dynamic models of the SynRM driving CVT system were derived. The blend recurrent Gegenbauer OPNNAPSO control system, which is comprised of the censor control, the recurrent Gegenbauer OPNN control with adaptive law and the recompensed control, is proposed to reduce and smooth the control torque and enhance robustness of system under the occurrence of the uncertainties. Moreover, based on Lyapunov stability theorem, the adaptive law of online parameter in the recurrent Gegenbauer OPNN is proposed. Furthermore, the learning rate of the parameter in the recurrent Gegenbauer OPNN by using APSO is proposed to achieve fast convergence. Finally, the control performance of the proposed blend recurrent Gegenbauer OPNNAPSO control system is more suitable than the well-known PI controller and the recurrent Gegenbauer OPNN control system with the fixed learning rate for the SynRM driving CVT system.

This work was supported by the Ministry of Science and Technology of Taiwan under grant numbers MOST 104-2221-E-239-011.

B-298

PQ-15

Integrated Design of Magnetic Gear and Electric Motor

for Electric Vehicles

Mi-Ching Tsai(a)*, Yi-Chang Wu(b), Chin-Tsung Chan(b), Pei-Yi Cai(c), Po-Wei Huang(c), and Ming-Hsiao Tsai(c)

(a) Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan (b) Department of Mechanical Engineering, National Yunlin University of Science & Technology, Yunlin, Taiwan

(c)Electrical Motors Technology Research Center, National Cheng Kung University, Tainan, Taiwan e-mail: mctsai@mail.ncku.edu.tw

A high efficient and compact power train system which is capable of achieving energy saving and overload protection is required in electric vehicles (EV). This paper aims to present a novel design of a driving motor integrated with magnetic gears for EV applications. A permanent magnet type of magnetic gear-motor with two air gaps is developed, and a finite-element analysis software tool is employed to simulate the magnetic field of the proposed design where the output performance, i.e. the investigated simulation results, such as the torque curve and rotational speed of the ring with iron pole-pieces versus time respectively are presented. A 3 kW magnetic gear-motor is proposed for the application of electric golf carts for its unique features of compact size, concentric configuration, high driving torque and maintenance free.

This paper has proposed a new 3 kW dual air-gap design of the magnetic gear-motor. The characteristics such as torque, gear ratio, speed and efficiency are investigated by 2D and 3D finite-element analysis. With the dual air gaps design, the motor is able to be operated on high efficiency range and high output torque but in smaller volume and lighter weight. A prototype of the proposed design will also be completed to verify the design and simulated results.

[1] P. Zheng, J. G. Bai, C. D. Tong, Y. Sui, Z. Y. Song, and Q. B. Zhao “Investigation of a Novel Radial Magnetic-Field-Modulated Brushless Double-Rotor Machine Used for HEVs,” IEEE Transaction on Magnetics, Vol.49, No.3, pp.1231-1241, 2013.

[2] P. Pisek, B. Stumberger, T. Marcic, P. Virtic, “Design Analysis and Experimental Validation of a Double Rotor Synchronous PM Machine Used for HEV,” IEEE Transaction on Magnetics, Vol.49, No.1, pp.152-155, 2013.

[3] L. Jian, K. T. Chau, and J. Z. Jiang, “A Magnetic-Geared Outer-Rotor Permanent-Magnet Brushless Machine for Wind Power Generation,” IEEE Transaction on Industry Applications, vol. 45, no. 3, pp. 954-962, 2009.

[4] W. N. Fu and S. L. Ho, “A Quantitative Comparative Analysis of a Novel Flux-Modulated Permanent-Magnet Motor for Low-Speed Drive,” IEEE Transaction on Magnetics, Vol. 46, No. 1, pp. 127-134, 2010.

[5] K. Atallah and D. Howe, “A Novel High-Performance Magnetic Gear,” IEEE Transaction on Magnetics, Vol. 37, No. 4, pp. 2844-2846, 2001.

[6] K. T. Chau, D. Zhang, J. Z. Jiang, C. Liu and Y. Zhang, “Design of a Magnetic-Geared Outer-Rotor Permanent-Magnet Brushless Motor for Electric Vehicles,” IEEE Transaction on Magnetics, Vol. 43, No. 6, pp. 2504-2506, 2007.

B-299

PQ-16

Magnetic and transport properties of epitaxial CoxFe3-xO4 thin films on MgO (100)

Quang Van Nguyen(a), Christian Meny(b), S. H. Rhim(a), Yooleemi Shin(b),

Duong Anh Tuan(a), and Sunglae Cho(a)

(a)Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of Korea

(b)Institute of Physics and Chemistry for Materials of Strasbourg, UMR 7504 UDS-CNRS, Strasbourg 67034, France

This study examined systematically the influence of the Co content on the

magnetic and transport properties of spinel CoxFe3-xO4 (0 ≤ x ≤ 1) epitaxial thin films

on a MgO (100) substrate prepared by molecular beam epitaxy. XRD measurement

confirmed the same spinel structure of our films. Electrical resistivity with the net of

n-type charge carriers was found to increase with increasing of Co concentration.

There was a ferromagnetic ordering with a reorientation of easy axis from in-plane in

un-doped towards to out of plane in Co doped films. This work opens a possibility to

incorporate CoxFe3-xO4 films as ferromagnetic electrodes with tunable transport and

magnetic properties in spintronic device.

B-300

PQ-17

Three-phase induction machines are reliable and widely used in industrial plants. The efficient condition

monitoring can diagnose the inception of fault mechanisms in induction motors thus avoiding failure and expensive repairs. Therefore, there is a strong need to develop a more efficient condition monitoring. The main target is to achieve a relatively low cost and/or non-invasive system which is still powerful in terms of monitoring for online detection of developing faults. This digest adresses rotor eccentricity faults and study of conventional monitoring techniques for induction motor faults. In order to reduce the UMP in case of an eccentric rotor, the eccentricity-generated additional airgap flux waves should be reduced. Additional, the characteristics of UMP in induction machines are addressed. Methods to reduce the side-band flux waves and hence attenuate the UMP will be addressed.

Table 1 : Summary of motor faults, percentage of failure, causes, and sensor signal used for faults detection

Faults Classification Failed Component Percentage IEEE EPRI

Causes Detections Methods

Electrical Faults

Rotor faults 8% 9% Thermal- stresses Corrosion Poor manufacturing

Stator current Axial Flux Vibration

Torque, speed

Stator winding faults 26% 36% Over-heating Over-voltages Mechanical stresses

Axial Flux Stator current

Mechanical

Faults Bearing faults 44% 41% Contamination

Improper installation and lubrication End of life

Stator current Vibration

Other faults (mainly – eccentricity causing unbalanced

magnetic pull)

22% 14% Bent Rotor Bearing wear Misalignment

Stator current Vibration Axial flux

[1] P. Vas, Parameter estimation, condition monitoring, and diagnosis of electrical machines, Oxford University Press,

USA, 1993. [2] P. J. Tavner and J. Penman, Condition monitoring of electrical machines, Research Studies Press, Wiley, New York,

1987. [3] L. K. Singh and P. K. S. Komal, "Condition Monitoring of Induction Motor," International Journal of Engineering

and Technical Research, Vol. 3, Iss. 4, April 2015. [4] Motor Reliability Working Group, "Report of large motor reliability survey of industrial and commercial

installations, Part II," IEEE Trans. Ind. Appl, vol. 21, pp. 865-872, 1985. [5] EPRI, "Improved Motors for Utility Applications," EPRI Final Report, 1982. [6] Y. Amirat, M. Benbouzid, B. Bensaker, and R. Wamkeue, "Condition monitoring and fault diagnosis in wind energy

conversion systems: a review," IEEE International Electric Machines and Drives Conference, IEMDC, pp. 1434-1439, 2007.

Monitoring and Damping UMP Due Eccentricity Fault in

Induction Machines: A Review

Ahmad Salah(a), David Dorrell(b) and Youguang Guo(a) (a)School of Electrical, Mechanical and Mechatronic Systems

University of Technology Sydney, Broadway, Sydney, NSW 2007, Australia (b)Discipline of Electrical, Electronic and Computer Engineering, Faculty of Engineering

University of KwaZulu-Natal, Howard College, Durban, 4041, South Africa Ahmad.salah@student.uts.edu.au; Dorrelld@ukzn.ac.za; Youguang.Guo-1@uts.edu.au

B-301

PQ-18

Flux switching machine (FSM) is a motor class which becomes popular in recent years. Among various FSM topologies, the single-phase DC-excited flux switching machine (DCFSM), which the PMs are replaced with field winding, has potential in low cost and high speed application such as home appliances. However, like the single-phase BLDC and SRM, the single-phase DCFSM suffers from low or null starting torque at some rotor positions which limits the applications of the single-phase DCFSM. In this paper, a single-phase 8-slot, 4-pole DCFSM is designed and a novel rotor structure which uses reluctance torque produced by field current is proposed to improve starting torque. The performance of the proposed single-phase DCFSM is analyzed with FEA software and the results are presented. The results show that the motor is able to deliver approximately 61% to 114% of the rated output torque, depending on the stop position, when starting.

Fig. 1. (a) Cross-sectional view. (b) Design parameters.

The design of a single-phase 8-slot, 4-pole DCFSM which contains a main rotor and auxiliary rotor to improve starting torque is presented in this paper. The main rotor produces the torque for normal operation and the auxiliary rotor provides reluctance torque to drive the whole rotor and load to the stable positions. It is predicted by FEA that the proposed design can deliver about 61% to 114% of the rated output torque at stable positions. The auxiliary rotor only needs to be added to the motor after the optimization procedure and the stack length of the auxiliary rotor can be adjusted to obtain requiring starting torque, which is flexible for design. Furthermore, the electromagnetic performance of the proposed design has less deterioration with slightly reduced power density and efficiency. [1] L. Mcgrow and C. Pollock, “Low Cost Brushless Generator,” IEEE Industry Applications Conference, 3-7 Oct. 1999.

[2] C. Pollock and M. Wallace, “The Flux Switching, a DC Motor without Magnet or Brushes,” IEEE Industry Applications Conference, 3-7 Oct. 1999.

[3] C. Pollock, H. Pollock, and M. Brackley, “Electronically Controlled Flux Switching Motors: a Comparion with an Induction Motor Driving an Axial Fan,” Industrial Electronics Society, IECON '03, 2-6 Nov. 2003.

[4] C. Pollock, H. Pollock, R. T. Walter, and B. V. Gorti, “Low Cost, High Power Density, Flux Switching Machines and Drives for Power Tools,” IEEE Industry Applications Conference, 12-16 Oct. 2003.

[5] Y. Cheng, C. Pollock, and H. Pollock, “A Permanent Magnet Flux Switching Motor for Low Energy Axial Fans,” IEEE Industry Applications Conference, 2-6 Oct. 2005.

Design of a Single-Phase DC-Excited Flux Switching Machine for

Home Appliance with Improved Starting Toque

Zih-Cing You*, Chung-Wen Yu, and Sheng-Ming Yang Department of Electrical Engineering, National Taipei University of Technology, Taiwan

*Contact e-mail: carefree60024@gmail.com

B-302

PQ-19

There are several reviews on magnetic gear driven permanent magnet machines, which can also be described as pseudo direct drives (PDDs) but there is still a lack of information about how to size and design these machines. In this paper, classical electrical machines sizing procedures are adapted to design a PDD for wind power application. The resulting PDD is compared with other permanent magnetic machines which are used as direct drives and mechanical gear drive machines.

(a) (b) (c)

Permanent magnet generators: a) direct drive machine, b) mechanical gear drive, and c) pseudo direct drives.

Power curves under different wind speeds.

TABLE I. UNIFIED MACHINE RATINGS

Rated wind turbine speed 136 rpm Rated phase voltage 220 V

Rated Power 10 kW Rated frequency 50 Hz

Vernier Structure Pseudo Repeat Pattern.

The estimated data of the three types of machines, namely the overall size, total weight, power density and material cost, are summarized in Tables II and IV for direct comparison. It can be observed that the proposed PDD has the highest power density compared with the DDM and MGD. In terms of material cost, the PDD is costlier than the MGD, but if the planetary gear is considered, the PDD is less expensive than the MGD. The cost of the PDD is almost 50% of cost of a DDM. Therefore, the proposed PDD is highly competitive for wind power generation. These are relatively small machines and there is further work to do in scaling the design up into the megawatt range. [1] L. Jian, G. Xu, Y. Gong, J. Song, J. Liang, and M. Chang, “Electromagnetic design and analysis of a novel

magnetic-gear-integrated wind power generator using time-stepping finite element method,” Prog. Electromagn.Res., vol. 113, no. Dec. 2010, pp. 351–367, 2011.

[2] D. E. Hesmondhalgh and D. Tipping, “A multielement magnetic gear,” IEE Proceedings, pt. B, vol. 127, pp. 129–138, 1980. [3] K. Atallah and D. Howe, “A novel high-performance magnetic gear,” IEEE Trans. on Magn., vol. 37, no. 4 I, pp. 2844–2846,

2001. [4] K. Atallah, J. Rens, S. Mezani and D. Howe, “Novel ‘pseudo’ direct-drive brushless permanentmagnet machine,” IEEE Trans. on

Magn., vol. 44, iss. 11, pp. 2195– 2198, 2008. [5] S. A. Nasar, I. Boldea and L. E. Unnewehr, Permanent Magnet, Reluctance, and Self-Synchronous Motors. CRC Press, 1993.

Design of a Pseudo Direct Drive for Wind Power Applications

C. G. C. Neves(a)*, A. F. Flores Filho(b), D. G. Dorrell(c)

(a)Curso de Eng. de Energia, Universidade Federal do Pampa, Brazil (b)DELET, Universidade Federal do Rio Grande do Sul, Brazil

(c)Discipine of Electrical, Electronic and Computer Engineering, Faculty of Engineering University of KwaZulu-Natal, Howard College Campus, Durban, 4041, South Africa

cgcneves@ieee.org, alyflores@ufrgs.br and d.g.dorrell@gmail.com

B-303

PQ-20

Two axis theory is generally used to model and analyze permanent magnet machine performance. Motor and generator parameters such as the d- and q-axis inductances are very important for the controller design. Nevertheless, traditional methods of determining parameters by testing is not viable if the field current cannot be controlled. Using power measurements and load angle computations, this study aims to determine the d-q inductances of a PM generator with Lq greater than Ld. Furthermore, the method will be applied to a conventional synchronous generator with constant field current and Ld greater than Lq. The results will be compared with those obtained by methods already well established.

The proposed method can be used as an alternative in order to calculate the load

angle and the result used to determine the saturated dq inductances of a PM machine. The results for load angle are not perfect for all load conditions because a constant value of Xd in 錯誤! 找不到參照來源。 was used. Good results for load angle prediction can be obtained at rated current values.

Although the slip test, in general, provides unsaturated parameters, this test can be done with rated voltage and current. In this way, saturated values of d-q inductances can be compared. With constant values of field current, there was more correlation between wound rotor machine Ld results. On the other hand, induced voltage variations could be a limiting factor in parameter determination. This fact will encourage the study of rotor temperature measurements since temperature can affect the results.

REFERENCES

[1] D. Carpenter, S. Deleanu, C. Nguyen, M. Lau, and M. M. Rahman, “A study on determination of parameters for permanent magnet synchronous machine by comparing load tests and Finite Element Analysis,” 2011 24th Can. Conf. Electr. Comput. Eng., pp. 000587–000592, 2011.

[2] H. P. Nee, “Determination of d and q reactances of permanent-magnet synchronous motors without measurements of the rotor position,” IEEE Trans. Ind. Appl., vol. 36, no. 5, pp. 1330–1335, 2000.

[3] P. H. Mellor, F. B. Chaaban, and K. J. Binns, “Estimation of parameters and performance of rare-earth permanent-magnet motors avoiding measurement of load angle,” IEE Proc. B Electr. Power Appl., vol. 138, no. 6, p. 322, 1991.

[4] IEEE Standard 1812, “Trial-Use Guide for Testing Permanent Magnet Machines.” IEEE, 2014. [5] B. J. Chalmers, “Performance of interior-type permanent-magnet alternator,” IEE Proc,-Electr. Power

Appl., Vol. 141, No. 4, July 1994.

Determination of dq Model Inductances in PM Generators

Guilherme Homrich(a)*, Aly F. Flores Filho(a), David G. Dorrell(b)

(a)PPGEE/LMEAE, Federal University of Rio Grande do Sul, Porto Alegre, Brasil (b)Discipline of Electrical, Electronic and Computer Engineering, Faculty of Engineering

University of KwaZulu-Natal, Howard College, Durban, 4041, South Africa guilherme.homrich@ufrgs.br; aly.flores@ufrgs.br; dorrelld@ukzn.ac.za

B-304

PQ-21

Switched reluctance motor (SRM) is superior from its robustness, simple structure and magnet-free, however it is suffered from torque ripple due to its highly nonlinear characteristics. If the torque ripple can be effectively reduced, SRM can be regarded as a great power device with marketing potential. To achieve lower torque ripple, a common control strategy: Torque Sharing Function (TSF) is studied. An improved TSF of a target SRM is developed in this paper, which includes speed controller and optimized look up table (LUT). Benefit and constrains will be discussed through Matlab/ Simulink simulations and experiments. The control methodology is superior to the traditional constant current controller while the torque output might be insufficient. The proposed controller is coupled with the TSF controller to compensate insufficient torque.

This research studies torque ripple reduction based on TSF strategy. The proposed method is validated experimentally. The reduction of torque ripple is considered to be significant.

Look up table

TSFstrategy

*mT TI

*( )m AT

*( )m BT

*( )m CT

*( )m AI

*( )m BI

*( )m CI

Position sensor

rm

rm

rm

mTasi

bsi

csi

dcV

Current control

AS

BS

CS

IT

Speed sensor

rm

Speed control

rm

*rm

Speed controller

0.41 0.415 0.42 0.425 0.432

4

6

8

0.41 0.415 0.42 0.425 0.430

10

20

30

40

50

0.375 0.38 0.385 0.39 0.3952

4

6

8

0.375 0.38 0.385 0.39 0.3950

10

20

30

40

50

0.1 0.2 0.3 0.4 0.5 0.6 0.70

5

10

Time(sec)

Tor

que

(N-m

)T

orq

ue(

N-m

)

Time(sec)

Torque ripple: 49.03%

Tor

qu

e(N

-m)

Time(sec)

Torque ripple: 80.68%

Without TSF With TSF

Time(sec)

Ang

le(d

egre

e)

An

gle(

deg

ree)

Time(sec)

[1] P. Jinupun and P. Chi-KwongLuk, “Direct Torque Control for Sensor-Less Switched Reluctance Motor Drives,”

Power Electronics and Variable Speed Drives, 1998. Seventh International Conference on (Conf. Publ. No. 456) [2] A.D. Cheok and Y. Fukuda, “A New Torque and Flux Control Method for Switched Reluctance Motor Drives,”

IEEE Transactions on Power Electronics, vol. 17, pp. 543-557, 2002. [3] X. D. Xue, K. W. E. Cheng, and S. L. Ho, “Optimization and Evaluation of Torque-Sharing Functions for Torque

Ripple Minimization in Switched Reluctance Motor Drives,” IEEE Transactions on Power Electronics, vol. 24, pp. 2076-2090, 2009.

[4] D.H. Lee, J. Liang, Z.G. Lee, and J.W. Ahn, “A Simple Nonlinear Logical Torque Sharing Function for Low-Torque Ripple SR Drive,” IEEE Transactions on Industrial Electronics, vol. 56, pp. 3021-3028, 2009.

Improved Non-Linear Torque Sharing Function Applied to

Torque Ripple Reduction of Switched Reluctance Motor

Min-Fu Hsieh(a)*, Chung Chan Hsu(a), Hao-Yu Ting(b), Po-Ying Li(b), Le-Ren Chang-Chien(b) and Yu-Hsien Li(a)1

(a) Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University, Taiwan (b) Department of Electrical Engineering, National Cheng Kung University, Taiwan

E-mail: mfhsieh@mail.ncku.edu.tw

FIG.I. Simulation environment of the TSF strategy FIG. II. Torque ripple compensation: with and without TSF

B-305

PQ-22

The purpose of this paper is to analyze the AC copper losses of the ironless brushless DC machine

(BLDCM) used in the Flywheel Energy Storage System (FESS). The influence factors of the AC copper losses, such as the winding diameter, current and machine speed etc. are analyzed. The research results show that the winding diameter has a huge effect on the winding AC loss in ironless BLDCM, and the shunt wound structure with multiple wires method can reduce winding AC loss effectively. However, due to induced voltage and impedance unbalance, additional circulating current loss would be induced. For circulating current losses calculation, a winding circulating current equivalent calculation model is built. The circulating current losses are calculated by simplified 3D finite element method and the winding strand arrangement method to reduce circulating current loss is explored. Three strands arrangements are compared and discussed. The results show that the ironless BLDCM using multi-strands with suitable strands arrangements can reduce the copper loss.

Fig. 1 The structure and the cross section of the ironless BLDCM

(a) D=1.9mm (b) D=1.34mm (c) D=0.6mm (fm=2kHz, fa=5kHz, Ia=20A, θa=0°)

Fig. 2 Current density distributions of conductors with different conductor diameter.

This paper has analyzed the AC copper losses of the ironless brushless DC machine (BLDCM) used in the FESS. The influence factors of the AC copper losses, such as diameter of the strands and the variation of the phase current has been discussed. For circulating current losses calculation, an equivalent circuit model is presented and effects of the analytical model parameters are given. Three strands arrangements are compared and discussed. The results show that the ironless BLDCM using multi-strands with suitable strands arrangements can reduce the copper loss. [1] EL-Refaie, A.M. , T.M. Jahns, Modified Vector Control Algorithm for Increasing Partial-Load Efficiency of

Fractional-Slot Concentrated Winding Surface PM Machines. Industry Applications Conference, 2006, vol. 1, pp. 50-57.

[2] Atallah, K., Howe, D., Mellor, P.H., Stone, D.A., Rotor Loss in Permanent-Magnet Brushless AC Machines, IEEE Transactions on Industry Applications, Nov/Dec 2000, vol. 36(6), pp. 1612-1618.

[3] V. d. Geest, P. Henk, Stator winding proximity loss reduction techniques in high speed electrical machines, IEMDC 2013, pp. 340-346.

[4] Jibin Zou, Kai Liu, Jianhui Hu, A Modified C-Dump Converter for BLDC Machine Used in a Flywheel Energy Storage System, IEEE Transactions on Magnetics, Oct 2011, vol. 47(10), pgs. 4175-4178.

AC Copper Losses Analysis of the Ironless BLDCM used in a

Flywheel Energy Storage System

Kai Liu, XinHe Fu, MingYao LinSchool of Electrical Engineering, Southeast University, Nanjin, China

B-306

PR-01

Anisotropic Sm-Co/α-Fe thick film-magnets prepared by two-step annealing

Yuya Furukawa*, Xu Han, Hiroaki Koga, Takeshi Yanai, Masaki Nakano, Hirotoshi Fukunaga

School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan

e-mail: bb52115245@ms.nagasaki-u.ne.jp Sm-Co/α-Fe nanocomposite magnets are attractive candidates for high performance magnets used at high temperatures because of their high Tc and Js values [1, 2]. We have already reported isotropic Sm-Co/α-Fe nanocomposite thick film-magnets with the (BH)max value of 100 kJ/m3 synthesized by the Pulsed Laser Deposition (PLD) method [3, 4].

The synthesis of anisotropic Sm-Co/α-Fe thick film-magnets is expected to increase in (BH)max significantly. On the other hand, long-time deposition on a high temperature substrate degrades magnetic properties of Sm-Co/α-Fe nanocomposite magnets by atomic diffusion between Sm-Co and α-Fe layers [4]. Therefore, we adopted the two-step annealing method [5]. In this study, we report magnetic properties of anisotropic Sm-Co/α-Fe thick film magnets prepared by the two-step annealing.

Sm-Co or Sm-Co/α-Fe films were deposited in vacuum on a Ta substrate by the PLD method from rotating Sm-Co or Sm-Co/α-Fe target. The substrate temperature Ts was varied between room temperature and 380 C. As the deposited films did not have coercivity, they were post-annealed at 600 °C for magnetic hardening.

The remanence ratio Jri/Jro (Jri and Jro: the remanences in the in-plane and out-of-plane directions, respectively) for Sm-Co films after post-annealing showed the peak at Ts =260 - 280C (Fig.1), which suggests that the highest in-plane anisotropy is achieved at this Ts range. Thus, we deposited a Sm-Co/α-Fe film at Ts =260C, and obtained an anisotropic Sm-Co/α-Fe nanocomposite thick film-magnet (Fig.2).

[1] H. Fukunaga et al., IEEE Trans. Magn. 49, 3240 (2013). [2] R. Horikawa et al., J. Appl. Phys. 115, 17A707 (2014). [3] H. Fukunaga, et al., IEEE Trans. Magn. 50, 2101504 (2014). [4] A. Tou et al., J. Appl. Phys. 115, 17A748 (2014). [5] Y. Zhang et al., J. Appl. Phys. 110, 053914 (2011).

Fig.1 Jri/Jro values after post-annealing as a function of Ts.

Fi 2 H i l f

B-307

PR-02

Effect of phase structure on remanence thermal stability of Alnico8 alloys

J.T.Zhao, Y.L.Sun, Z.Liu, D.Lee,L.Liu, X.C.Feng and A.R.Yan

Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of

Material Technology and Engineering, ChineseAcademy of Sciences,Ningbo, 315201, China

With the development of technology and application requirements, researchers pay attention to not only magnetic properties of Alnico alloy but also its thermal stability. Their magnetic properties keeps in closely touch with phase microstructure[1], also Liu focuses on the effect of orientation degree of precipitated phase on thermal stability[2]. This paper mainly studies the influence of phase structure to thermal stability of Alnico8 alloys by adjusting the contents of Co and Nb(Sample A:36wt%Co; Sample B:36wt%Co, 1.1wt%Nb; Sample C:35wt%Co, 1.1wt%Nb). The morphology is characterized by Transmission Electron Microscope, the magnetic properties are measured by the B-H apparatus with closed circuit.

The room-temperature magnetic properties of remanence, coercivity and magnetic energy product of Sample C is 10.92KGs, 1695Oe and 12.48MGOe respectively. Fig. 1 shows Nb will decrease fluctuation of the temperature coefficient of remanence(short for a), meanwhile decreasing the content of Co is favorable to decrease the a. The a(RT-180) of Sample C is -1.26%%/. The white arrows indicate Nb can improve the uniformity of distribution and morphology of the precipitated phase and stop the small precipitated phase in the matrix phase(as showed in Fig. 2(a)、2(b)、2(c)). The white circle manifest the bifurcation phenomenon of the precipitated phase diminish gradually reducing further the content of Co, which will enhance the length and orientation degree of the precipitated phase(as showed in Fig. 2(d)、2(e)、2(f)). XRD analysis shows from Sample A to Sample C the orientation degree of precipitated phase indicated by I100/I200 gradually increase. Sample C shares the highest the sum content of Fe、Co and nFe/nCo in the precipitated phase, which means phase composition distribution is more homogeneous. The outstanding orientation degree and well-distribution of the precipitated phase promote Alnico8 alloys to get excellent thermal stability. Meanwhile the higher the sum of Fe、Co and nFe/nCo in the precipitated phase may have the similar effect as well.

[1] Lin Zhou, M.K. Miller, et al., Architecture and magnetism of alnico, Acta Mater, 74(2014) 224-233.

[2] Tao Liu, Wei Li, et al., Effect of Co on the thermal stability and magnetic properties of Alnico 8 alloys, J. Appl.

Phys. 115, 17A751(2014).

Fig. 1 The curve of the remanence temperature coefficient against temperature of Alnico8 alloys

Fig. 2. TEM images of Alnico8 alloys: (a) Sample A,

transverse; (b) Sample B, transverse; (c) Sample C,

transverse; (d)Sample A, longitudinal; (d)Sample B,

longitudinal; (d)Sample C, longitudinal.

B-308

PR-03

Effect of bath temperature on structural and magnetic properties of Fe22Ni78 films electroplated in a

deep-eutectic-solvent-based bath K. Azuma, T. Akiyoshi, T. Yanai, M. Nakano, H. Fukunaga

Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Email: bb52115201@cc.nagasaki-u.ac.jp Deep Eutectic Solvents (DES) are expected as a new solution for plating bath. It is

well-known that the bath temperature is one of dominant factors to determine film properties such as surface roughness and magnetic properties. In order to investigate the effect of the bath temperature on film properties, we plated Fe22Ni78 films in the DES-based baths with various temperatures.

The DES was prepared by stirring the mixture which consists of ethylene glycol and choline chloride. FeCl2·4H2O and NiCl2·6H2O were added into the above-mentioned DES. The bath temperature was changed from 60 to 140 C. 　

Figure 1 shows current efficiency as a function of bath temperature. The current efficiency increases with the increasing the bath temperature from 60 to 80 °C, and shows almost constant values in high bath temperature region. Typical DESs have high viscosity [1], and the viscosity strongly depends on bath temperature. Therefore, we consider that low current efficiency at low bath temperature is attributed to high viscosity of the DES. Figure 2 shows XRD patterns of the films. As-shown in Fig. 2, line broadening take place when the bath temperature is low. This result implies that low bath temperature are effective in reducing the grain size. Since the effective magnetocrystalline anisotropy could be reduced by grain refinement, we concluded that moderate high bath temperature at 80-120 C to obtain efficiently the Fe22Ni78 films with good soft magnetic properties. [1]A.P. Abbott et al., Chem. Commun., 9 (2003) 70.

Fig.1. The current efficiency and M-H

loop of the as-plated Fe22Ni78 films as a

function of bath temperature

Fig.2. X-ray diffraction patterns of

the Fe22Ni78 films electroplated at

various bath temperatures.

B-309

PR-04

High-speed Fe plating using DES-based plating baths

T. Akiyoshi, K. Azuma, T. Yanai, K. Eguchi, M. Nakano, H. Fukunaga

Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan e-mail: bb35212003@ms.nagasaki-u.ac.jp

Recently, we reported magnetic Fe films plated in Deep-Eutectic-Solvent-based plating baths, and clarified that a DES is one of attractive solvents due to high plating rate (approx. 120 μm/h) and high current efficiency (> 90 %) [1]. In order to further increase the plating rate, we focused on the current density during the plating. In the present study, we investigated the effect of the current density on plating rate, magnetic properties and surface roughness of the Fe film.

We plated the Fe films using a constant direct current. A DES was made from the mixture of choline chloride (10 g) and ethylene glycol (10 g), and FeCl2·4H2O was added in the DES. The bath temperature was fixed at 100 °C, and the total supplied charge to the cathode was kept at 60 C.

Figure 1 shows plating rate as a function of current density. As shows in Fig.1, the increase in the current density improves the plating rate, and we found that the maximum plating rate depends on the FeCl2 concentration.

Figure 2 shows the arithmetic average of surface roughness Ra as a function of current density. The inset indicates the hysteresis loops of the Fe films prepared at 0.1 or 2 A/cm2. The surface roughness is clearly affected by the FeCl2 concentration, and we found that high FeCl2 concentration is effective to obtain the Fe films with smooth surface. Without deteriorations of the surface roughness and the magnetic properties, we consequently obtained a high plating rate value of approximately 930 μm/h by the increase in the current density and the FeCl2 concentration, and we concluded that the DES is one of hopeful solvents for high speed plating.

[1] T. Yanai et al., J. Appl. Phys., 115 (2014) #17A344.

Fig.1 Plating rate as a function of current density.

Fig.2 Surface roughness Ra as a function of current density.

B-310

PR-05

Fe-Pt thick films prepared by a pulse plating method

T. Masaki, T. Yanai, K. Furutani, M. Nakano, H. Fukunaga Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Email: bb52115249@ms.nagasaki-u.ac.jp

We have already reported Fe-Pt thick films prepared by an electroplating method [1].

Although we obtained large coercivity in the previous study, reduction in large cracks

of the film was a problem to be overcome. In the present study, we focused on increase

in the bath concentration in order to reduce large cracks.

The plating bath was consist of FeSO4·7H2O (10 - 500 g/L), Pt(NH3)2(NO2)2 (10

g/L), citric acid (30 g/L), and NH4Cl (25 g/L). For pulse plating, we employed cycle

time T = 1 sec, ON time Ton = 0.2 sec, current density j = 2 or 3 A/cm2. In order to

promote the phase transformation from fcc (face centered cubic) to fct (face centered

tetragonal), the films were annealed. The annealing temperature and annealing time

were 700 C and 60 min, respectively.

Figure 1 shows SEM images of the Fe-Pt films prepared in the baths with various

FeSO4 contents at j = 2 and 3 A/cm2. 10 g/L of the FeSO4 corresponds to

previously-reported content [1]. Although large cracks were observed when the FeSO4

content were low, the cracks were reduced by the increase in the the FeSO4 content.

Figure 2 shows hysteresis loop of the annealed Fe40Pt60 film prepared in the baths

with high FeSO4 content. The coersivity was approximately 700 kA/m, and almost the

same value as Fe50Pt50 film reported in Ref [1].

From these results, we found that slight increase in the bath concentration is

effective to reduce the cracks without large deterioration of hard magnetic properties.

-2000 -1000 1000 2000

-1.2

-0.8

-0.4

0.4

0.8

1.2

0H [kA/m]

M/M

max

Ref [1]

Current density:3A/cm2

FeSO4:100g/L

Fig. 1 SEM imagnes of the Fe-Pt films. Fig.2 Hysteresis loops of the annealed flims. [1] T. Yanai et al., J. Appl. Phys., 117 (2015) #17A744.

B-311

PR-06

Effect of an additive in DES-based baths on magnetic properties of electroplated magnetic films

T. Akiyoshi, K. Azuma, T. Yanai, K. Eguchi, M. Nakano, H. Fukunaga

Nagasaki University, Nagasaki-City, Nagasaki 852-8521, Japan e-mail: bb35212003@ms.nagasaki-u.ac.jp

Recently, we have reported Fe-Ni films electroplated in Deep-Eutectic-Solvent-based plating bath, and confirmed that the DES-based bath shows high current efficiency (> 90 %) [1]. In our previous studies, we did not use any additives for improvement in levelling and brightness of the films. As studies on additives in DES-based baths are not enough, we focus on phenanthroline, which is used as complex agent [2-3], as an additive. In this study, we investigated the effect of the phenanthroline compounds to improve surface roughness and soft magnetic properties.

We plated the Fe22Ni78 films using a constant direct current. A DES was made from the mixture of choline chloride (10 g) and ethylene glycol (10 g), and FeCl2·4H2O and NiCl2·6H2O were added in the DES. 1,10-phenanthroline is used as an additive.

Figure 1 shows SEM images of Fe22Ni78 films prepared in the baths with the phenanthroline content of 0, 20 and 40 mg at 100 C. The surface morphology was changed by the additive, and the additive improved the surface roughness. Figure 2 shows the coercivity as a function of the phenanthroline content. As shows in Fig.2, an increase in the additive content tends to reduce the coercivity. Therefore, we concluded that the phenantrorline is an effective additive to improve the surface roughness and the magnetic properties of the Fe-Ni films prepared from the DES-based plating baths. [1] T. Yanai et.al, J. Appl. Phys. 115, 17A344 (2014).

[2] G. D. Storrier et.al, Inorg. chem. 38, 559 (1999)

[3] J. M. Hartley et.al, Inorg. chem. 53, 6280 (2014)

Fig.1 SEM images of Fe22Ni78 films.Fig.2 The coercivity as a function of the phenanthroline content.

B-312

PR-07

Investigation of magnetic properties of electroplated permalloy for flux-guide application

Bipul Das(a), Meng-Syun Jhou(a), Cheng-Yun Lee(a), C. H. Lee(b), J. T. Jeng(c), Van Su Luong(c), J. H. Hsu(d), C. R. Chang(d), Lance Horng(a) and

Jong-Ching Wu(a)

(a)National Changhua University of Education, Changhua 500, Taiwan (b)National Tsing Hua University, Kuang-Fu Road, Hsinchu 30013, Taiwan

(c)National Kaohsiung University of Applied Sciences, Chien Kung Road, Kaohsiung 807, Taiwan

(d)National Taiwan University, Roosevelt Road, Taipei 10617, Taiwan e-mail: bipudl@gmail.com

Here, we investigate magnetic properties of electroplated on-chip Py films to

integrate it as flux guide in a three dimensional GMR based magnetic field sensor. Py films of different thicknesses (~ 10 to 200 µm) are electroplated onto patterned Si/SiO2 wafers using electroplating technique. Electroplating under higher current densities (J) leads to lower Ni atomic concentration (Ni%) in the films. The coercivity decreases with increasing the film thickness (Fig.1a) under various current densities. XRD patterns confirm their fcc crystalline structure. Py with Ni% ~ 81% shows exponentially decreasing initial permeability (µ0) with increasing film thickness (Fig.1b). Overall low magnitude and systematic decay of µ0 with increasing film thickness is understood with the help of microstructure and crystalline structure of the films. Grain size and porosity contributions to the permeamibility for a particular film thickness do not differ much at other film thicknesses. However, the XRD patterns indicate the presence of induced residual stresses in all the films. And, it is the amount of residual stress in the films that eventually determines µ0. We believe proper manipulation of residual stresses and of Ni% in our low coercive (~ 0.25 Oe to 1.4 Oe) films will enhance the permeability significantly and will fulfil our prime requirement of guiding an external magnetic field considerably.

0 60 120 180 2400.0

0.6

1.2

1.8

30 mA/cm2

40 mA/cm2

50 mA/cm2

60 mA/cm2

70 mA/cm2

HC (

Oe)

Plating time (min)

(a)

0.0 1.0x10-4 2.0x10-4

0

100

200

300

40010 m thick film

-300 -150 0 150 300

-0.1

0.0

0.1

0.2

Mag

netiz

atio

n (e

mu)

H(Oe)

Init

ial P

erm

eab

ilit

y(G

/Oe)

Thickness(m)

(b)

Figure 1: (a) Coercivity versus plating time for all the films synthesized under different current densities. (b) Initial permeability of the films that are synthesized under the 50 mA/cm2 current density is plotted against the film thickness, (inset) Hysteresis loop of the film with thickness 10 µm.

B-313

PR-08

Production of nanocrystalline Fe-Si-B-P-Nb-Cu alloys with excellent soft magnetic properties for commercial applications

Zongzhen Li, Shaoxiong Zhoua, Guangqiang Zhang, Bangshao Dong, Hui Gao China Iron & Steel Research Institute Group, Advanced Technology & Materials Co., Ltd.,

Beijing 100081, China aemail: sxzhou@atmcn.com

The present investigation deals with the processing of Fe–Si–B–P–Nb–Cu

nanocrystalline ribbons by using a planar flow melt spinning (PFMS) and subsequent

isothermal annealing. It is found that the replacement of B with optium Si is quite

effective for obtaining a finer and uniformer nanocomposite microstructure composed

of densely packed α-Fe grains after annealing. However, too much addition of Si at the

expense of B reduces the glass forming ability of the alloy, which results in lower

reproducibility. The Fe82.25Si6B7P3Nb1Cu0.75 alloy exhibits excellent soft-magnetic

properties, including the high saturation magnetic flux density up to 1.73T, low

coercivity of about 2.5 A/m and high effective permeability of 2.8×104 at 1 kHz under a

field of 1 A/m. The higher magnetization, higher glass forming ability and lower

materials cost compared with Finemet alloys make this alloy promising for mass

application of high energy efficient power transformers and motors.

B-314

GA-01

Microstructure and magnetism of a Nd-Fe-B sintered magnet

investigated using synchrotron X-rays

Tetsuya Nakamura 1) Japan Synchrotron Radiation Research Institute (JASRI) / SPring8

2) ESICMM / NIMS

Nd-Fe-B sintered magnets are the best permanent magnets that have ever been obtained [1], and are used in a wide variety of applications such as energy-saving appliances, (hybrid) electric vehicles, wind power generators, and so on. In these applications, the magnets are used for motors which require higher coercivity in order to be robust against demagnetization fields. Therefore, significant improvement of the coercivity is currently the most important subject in studies of Nd-Fe-B sintered magnets. The grain sizes and orientations of Nd2Fe14B crystals in the sintered magnet affect the coercivity because of the local demagnetization field and magnetic dipole interaction, respectively. Additionally, the chemical and magnetic properties of the grain boundary (GB) phase are also important factors for determining the coercivity because the GB phase functions as a pinning site. These features directly indicate that uncovering the relationship between the microstructure and the coercivity of Nd-Fe-B sintered magnets is crucial to manufacturing higher coercivity Nd-Fe-B sintered magnets.

The thin-film-like GB phase exists between neighboring Nd2Fe14B grains and is preferred to be paramagnetic so as to prevent reversed magnetic domains from expanding into neighboring grains. Although the GB phase was believed to be paramagnetic for a long time, we showed, through application of the X-ray magnetic circular dichroism (XMCD) technique, that the GB phase of a Nd14.0Fe79.7Cu0.1B6.2 sintered magnet is ferromagnetic and that the Curie temperature is lower than that of the Nd2Fe14B crystals by about 50 K [2]. This result implies that decreasing the Curie temperature could improve the coercivity. In this study, we have confirmed that the coercivity of the fractured surface closely resembles that of the bulk, contrary to the polished surface in which the coercivity is significantly decreased. The higher coercivity of the fractured surface is attributed to a GB fracturing property of the Nd-Fe-B sintered magnet, in which the majority of the surface remains covered with the thin GB phase layer.

Conventional magnetic domain observations have normally been conducted on polished surfaces or thin films using Kerr microscopy, magnetic force microscopy, and photoelectron emission microscopy. However, these methods are not applicable to magnetic domain observations of the fractured surface. In order to observe the magnetic domain structure in the fractured surface, we have developed a new scanning X-ray microscope (SXM) instrument equipped with a superconducting magnet with a maximum magnetic field of 8 T. When used in combination with the XMCD measurement and total-electron-yield detection, magnetic domain observations of the fractured surface become possible. In the magnetic domain observations of the fractured surface of the Nd14.0Fe79.7Cu0.1B6.2 sintered magnet, both the microstructure and the magnetic domain contrast are clearly observed. The magnetic field dependence of the magnetic domain structure has shown that the local area which initially generates the reversed domains is always identical and independent of whether the magnetic field is increased or decreased.

Acknowledgements

Part of this work is supported by the Elements Strategy Initiative Center for Magnetic Materials under the outsourcing project of MEXT.

References [1] M. Sagawa, S. Fujimura, N. Togawa, H. Hashimoto, and Y. Matsuura, J. Appl. Phys. 55, 2083 (1984).

[2] T. Nakamura, A. Yasui, Y. Kotani, T. Fukagawa, T. Nishiuchi, H. Iwai, T. Akiya, T. Ohkubo, Y. Gohda, K. Hono, and

S. Hirosawa, Appl. Phys. Lett. 105, 202404 (2014).

B-315

GA-02

Compact STXM: Development and Application for Magnetic Materials

Y. Takeichi(a)

(a)Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801 Japan

e-mail: yasuo.takeichi@kek.jp

Spectroscopy using synchrotron X-rays has been played an important roll in understanding magnetic materials, since the method provides element-specific information of electronic properties and magnetism. Spatially resolved soft X-ray absorption spectroscopy has been realized as scanning transmission X-ray microscopy (STXM) [1]. An STXM combined with X-ray magnetic circular dichroism (XMCD) realizes an investigation of electronic properties and magnetism with a spatial resolution of tens of nanometres [2]. However, there was no instrument of STXM with XMCD available in Asia until recently.

We have developed a new design of an STXM instrument at the Photon Factory, Japan [3]. The microscope is designed in a very compact shape so that it realized (i) mobility of the instrument that is easily connected to and removed from the existing synchrotron beamlines, whereas having (ii) vibrational stability that realizes a spatial resolution limited by the Fresnel zone plate, and (iii) thermal stability with the image drift of less than 100 nm during a measurement of 1–2 hours. The control electronics and software were developed under LabVIEW platform to realize a stand-alone device for a fast scanning operation [4]. An APPLE-II type undulator at BL-13A provides horizontal- and vertical-linear, circular and elliptical polarization in the photon energy range of 250–1700 eV, including L-edges of 3d transition metals and M-edges of rare earths.

We have performed magnetic domain observations and selected-area spectroscopies on various permanent magnets. Clear domain pattern observed with the STXM enables us to visualize the dipole interaction energy distribution [5]. Selected area XMCD spectrum reveals the electronic properties of rare-earth elements that play an important roll in the coercivity mechanisms.

[1] A. L. D. Kilcoyne, T. Tyliszczak, W. F. Steele, S. Fakra, P. Hitchcock, K. Franck, E. Anderson, B. Harteneck, E. G. Rightor, G. E. Mitchell, A. P. Hitchcock, L. Yang, T. Warwick, and H. Ade, J. Synchrotron Rad., 10, 125 (2003). [2] K. Ono, T. Araki, M. Yano, N. Miyamoto, T. Shoji, A. Kato, A. Manabe, H. Nozaki, Y. Kaneko, and J. Raabe, IEEE Trans. Magn., 47, 2672 (2011). [3] Y. Takeichi, N. Inami, H. Suga, C. Miyamoto, T. Ueno, K. Mase, Y. Takahashi, and K. Ono, Rev. Sci. Instrum., 87, 013704 (2016). [4] N. Inami, Y. Takeichi, and K. Ono, J. Phys.: Conf. Ser., 502, 012011 (2014). [5] H. Ohtori, K. Iwano, C. Mitsumata, Y. Takeichi, M. Yano, A. Kato, N. Miyamoto, T. Shoji, A. Manabe, and K. Ono, J. Phys.: Conf. Ser., 502, 012010 (2014).

B-316

GA-03

Realization of Ground-State Artificial Skyrmion Lattices at Room Temperature

Dustin A. Gilbert(a),(b), Brian B. Maranville(b), Andrew L. Balk(c),(d), Brian J. Kirby(b), Peter Fischer(e),(f), Daniel T. Pierce(c), John Unguris(c),

Julie A. Borchers(b) & Kai Liu(a)

(a)Department of Physics, University of California, Davis, California 95616 (b)NIST Center for Neutron Research, National Institute of Standards and

Technology, Gaithersburg, Maryland 20899 (c)Center for Nanoscale Science and Technology, National Institute of Standards

and Technology, Gaithersburg, Maryland 20899 (d)Maryland Nanocenter, University of Maryland, College Park, Maryland 20742

(e)Center for X-Ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720

(f)Department of Physics, University of California, Santa Cruz, California 94056 e-mail: dustin.gilbert@nist.gov; kailiu@ucdavis.edu

Magnetic Skyrmions exhibit topologically protected quantum states, not only offering exciting new mechanisms for ultrahigh density and low dissipation information storage, but also providing an ideal platform for explorations of unique topological phenomena. Prerequisite are systems exhibiting skyrmion lattices at ambient conditions. Here, we demonstrate the realization of artificial Bloch skyrmion lattices over extended areas in their ground state at room temperature by patterning asymmetric magnetic nanodots with controlled circularity on an underlayer film with perpendicular magnetic anisotropy (PMA) [1], shown in Fig. 1. Polarity is controlled by a tailored magnetic field sequence and

demonstrated in magnetometry measurements. The chiral structure is imprinted from the dots into the underlayer by selectively suppressing the PMA under the dots via a critical ion irradiation step. The imprinted skyrmion lattices are identified directly with polarized neutron reflectometry and confirmed by magnetoresistance measurements. Our results demonstrate an exciting platform to explore room temperature ground state Bloch skyrmion lattices.

This work has been supported by the NSF (DMR-1008791 and ECCS-1232275),

the NRC RAP (DAG), and DOE BES MSE Contract No. DE-AC02-05-CH11231 (PF).

[1] D. A. Gilbert, B. B. Maranville, A. L. Balk, B. J. Kirby, P. Fischer, D. T. Pierce, J. Unguris, J. A. Borchers, and Kai Liu, Nature Commun., 6, 8462 (2015).

Figure 1 Diagram of an

artificial Skyrmion Lattice

B-317

GA-04

Spin torque in topological insulator thin films Z.B. Siu(a), M.B.A. Jalil(a) and S.G. Tan(b)

(a) National University of Singapore, Singapore (b) Data Storage Institute, Singapore

e-mail : elesiuz@nus.edu.sg Topological insulator (TI) thin films [1] differ from semi-infinite slabs of TI in that the former possess both top and bottom surface, each of which supports surface states. In this work, we study the accumulation on a TI thin film of infinite

dimensions along the and directions, and finite thickness along the z direction modeled by the Hamiltonian

(We have set .) The ’s represent real spin, the localization of the states

nearer the top / bottom surfaces, and the coupling between the two surfaces. The last

term introduces an asymmetry between the surfaces. We calculate the spin z accumulation resulting from the passage of an electric field using the Kubo formula. This spin accumulation exerts a torque on the magnetization. In the absence of the inter-surface coupling and the terms, the

dispersion relation consists of two separate Dirac cones corresponding to .

Even after the term has been turned on, most of the space points on the Equal

Energy Contours (EEC’s) at a given value of energy can be identified with one of the

two Dirac cones. The sign of the spin accumulation at each k space point on the EEC can then be understood in terms of how the spin orbit interaction field rotates when the momentum component in the direction of the field in increased [2]. A finite value of breaks the anti-symmetry of the spin accumulation and results in a finite spin z accumulation integrated over the entire EEC.

Fig. 1. (left) The spin z polarization integrated over the entire EECs as a function of energy E and

intersurface coupling . (right) The spin z accumulation at various points on the EEC at the (E, ) values indicated. [1] C-X Liu et al, Phys. Rev. B 81, 041307 (2010); H-Z Lu et al, Phys. Rev. B 81, 115406 (2010). [2] T. Fujita, M.B.A. Jalil and S.G. Tan, New J. Phys. 12, 013016 (2010); S.G. Tan and M.B.A. Jalil, J. Phys, Soc. Jpn. 82, 094714 (2013).

B-318

GA-05

Long-range transfer of electron-phonon coupling in BFO-based heterostructures

Ping-Fan Chen,(a) Yen-Lin Huang,(b) Jan-Chi Yang,(b) Heng-Jui Liu,(b) Jiunn-Yuan Lin,(c) Ying-Hao Chu.(a),(b)

(a)Institute of Physics, Academia Sinica, Taipei 11529

(b)Department Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010

(c)Institute of Physics, National Chiao Tung University, Hsinchu 30010

We selected the BiFeO3 (BFO) with 71o periodic ferroelectric (FE) domains as template to control the EPS in La2/3/Ca1/3MnO3 (LCMO), and this 71o stripe domain structure was along [001]o direction. BFO is one of the rare compounds exhibiting both a large FE polarization and antiferromagnetic order above room temperature, and further these periodic domains can offer additional electric, magnetic and structural perturbation to the above manganite layer. We found that the resistivity difference along the two in-plane orthogonal directions ([001]o and [1-10]o) could be observed in the 40-nm single LCMO films, while no change with the metal-insulator transition temperature (TMI) is induced. Interestingly, when fabricated with the 71o-BFO template, along those two orthogonal directions, not only the difference of resistivity, but also the change of TMI can be obviously obtained in this 40-nm LCMO layer. It shows that the TMI of the LCMO layer in the [1-10]o direction which is vertical to the FE stripe domain can be suppressed by 30 K. Even when we reduced the thickness of LCMO to 25 nm, this LCMO/BFO heterostructure can simultaneously integrate macroscopic metal- and insulator-like transport behavior. We presumed that the anisotropic strain provided by the 71o strip-domain structure would rebuild the pattern of electronic phase separation in LCMO layers, accompanied by the giant anisotropy influenced by the additional various couplings among spin, orbital, charge perturbations.

B-319

GA-06

Fig. 1 Switching efficiency compared with inverse magnetization. The x-axis represents sputtering power of Gd in Watts with Co power kept constant at 120 Watts.

High switching efficiency in ferrimagnet spin-orbit torque devices

Rahul Mishra, Xuepeng Qiu and Hyunsoo Yang

Department of Electrical and Computer Engineering, National University of Singapore, Singapore

e-mail: eleyang@nus.edu.sg

Spin-orbit torques (SOT) have been studied recently for its potential applications in MRAM and logic devices. So far it has been most widely studied in thin films with perpendicular magnets such as Pt/Co/(MgO or Al2O3). These thin films studied typically have a very low coercivity and are thermally unstable due to their sub nano-meter thicknesses, which is not ideal for device applications. We study switching of rare earth (RE) ferrimagnet CoxGd1-x for different compositions. Devices from the structure of Pt (10 nm)/CoxGd1-x (6 nm)/TaOx (1 nm) show a high switching efficiency and maximum effective spin orbit field value near the compensation composition of CoxGd1-x. The longitudinal effective field has a value of 5500 Oe/10-8 Am-2 while the switching efficiency has a peak value of ~ 1510-8 Oe/Am-2 near compensation. These values are quite high compared to that from ferromagnetic systems, in which the switching efficiency is ~1.510-8 Oe/Am-2 [1] and an effective longitudinal field is ~ 500 Oe/10-8 Am-2 [2]. The scaling of the effective field with different Co-Gd compositions is not proportional to the scaling of the saturation magnetization (Ms). We attribute this to the negative exchange coupling between the sub-lattice of Co and Gd. Negative exchange coupling makes the ferrimagnet thermally stable near compensation by increasing its anisotropy and also provides the exchange coupling torque that helps in switching when current is applied, effectively increasing the overall switching efficiency of ferrimagnetic SOT devices. [1] X. Qiu, K. Narayanapillai, Y. Wu, P. Deorani, D.-H. Yang, W.-S. Noh, J.-H. Park, K.-J. Lee, H.-W. Lee, and H. Yang, Nat. Nanotechnol., 10, 333 (2015) [2] K. Garello, I. M. Miron, C. O. Avci, F. Freimuth, Y. Mokrousov, S. Blügel, S. Auffret, O. Boulle, G. Gaudin, and P. Gambardella, Nat. Nanotechnol., 8, 587 (2013)

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GB‐01

Effect of Interface-Assisted Molecular Ordering on the Operation of Organic Spintronic Devices

Tae Hee Kim

Dept. of Physics, Ewha Womans University, Seodaemun-gu, Seoul 03760, Rep. of

Korea

In the last decade, spin-related phenomena in organic semiconductors (OSCs) have been

actively explored. Exploration of spintronic devices integrated with organic materials is a hot

subject attracting many researchers for providing the non-volatility, high speed, and low

energy consumption of magnetic memory although magnetic metals have large impedance

mismatches with organics. The greatest advantage of the combination of organic materials

with inorganic electrodes is the possibility to develop new hybrid organic-inorganic devices

based on spin preservation on long time scales. A more ambitious approach has been taken to

tailor interface properties precisely at the molecular level, offering ever new possibilities in

spintronics.

We gave our efforts to develop organic spintronic devices with a long spin diffusion

length by improving the interface properties and molecular ordering of OSC. Here we report

the role of an ultrathin MgO interlyer as an ideal platform to form the ordered structure of

Cu-phthalocyanine (CuPc). For the 1.6-nm-thick CuPc films on MgO(001), homogeneous

polymorphs of CuPc films in the perpendicular direction and in-plane alignment of CuPc

stacking axis were observed by Raman spectroscopy and RHEED studies. As a result, for

Fe/1.6 nm MgO(001)/ 1.6 nm CuPc/Co junctions, remarkable magnetoresistance (MR) values

higher than 100% were observed at 77 K with strong bias dependence, while the MR values

of around 6% were measured at 300 K. The details of Raman and RHEED studies revealed

the temperature and thickness dependences of MR values were correlated to the in-plane

alignment of CuPc molecules on the MgO(001). Our results highlight that both in-plane and

out-of-plane molecular orderings are strongly coupled to the electric and magnetic properties

of organic-based devices, and are key factors for the effective spin transport phenomena.

B-321

GB‐02

Vortex-state nanoparticles for bio-imaging and magnetic hyperthermia

Sang-Koog Kim National Creative Research Initiative Center for Spin Dynamics and Spin-Wave

Devices, Nanospinics Laboratory, Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul

151-744, South Korea Bio-imaging and bio-medicine industries have grown significantly in pursuit of

earlier diagnosis of, and more timely therapy for, human diseases. MRI (Magnetic Resonance Imaging) is becoming more widely used to visualize internal organs and structures of the human body. To be able to take full advantage of MRI’s and other bio-imaging techniques’ special utility, however, it is essential that their signal sensitivity and spatial resolution be improved to the point that tumor-candidate cells can be isolated and identified. Currently one of the most promising MRI modalities involves the use of contrast agents constituted of super-paramagnetic nanoparticles. Yet this

technique requires the application of extremely high magnetic fields (1 7 Tesla) to obtain a sufficient number of net signals. The generation of fields of such strength incurs significant cost in superconductor maintenance, and moreover, could have as-yet-unknown side-effects on the human body. Thus, it is necessary to find a new,

innovative approach one that entails extremely high-sensitivity, high-spatial-

resolution, yet low-magnetic-field bio imaging and to develop the relevant diverse and proven applications to in-vivo diagnosis and therapy.

To this end, we report for the first time that the resonantly excited precession and reversal dynamics of vortex cores in soft magnetic nanoparticles and their size-specific resonant effect [1] may be used to develop new-paradigm bio-imaging techniques as well as hyperthermia therapy. These approaches, though challenging, are very creative. In this presentation we will report the synthesis of vortex-state nanoparticles [2], micromagnetic numerical calculations of novel vortex-state particles’ dynamics [1] as well as the concept of the use of those particles and novel spin dynamics for bio-imaging and hyperthermia applications. This concept will provide the original and core technologies that exceed the limitations of conventional bio-imaging tools and therapy to realize the simultaneous implementation of bio-imaging diagnosis and immediate therapy. [1] S.-K. Kim et al., Sci. Rep. 5, 11370 (2015). [2] M.-K. Kim et al, Appl. Phys. Lett. 105, 232402 (2014).

B-322

GB‐03

Spin polarized tunneling study on spin Hall effect metals and topological insulators

Luqiao Liu

Electrical Engineering & computer Science, MIT

Spin orbit interactions give rise to interesting physics phenomena in solid state

materials such as the spin Hall effect (SHE) and topological insulator surface states. Those effects have been extensively studied using various electrical detection methods. However, to date most experiments focus only on characterizing electrons near the Fermi surface, while spin-orbit interaction is expected to be energy dependent. Here we developed a tunneling spectroscopy technique to measure spin Hall materials and topological insulators under finite bias voltages. By electrically injecting spin polarized electrons into spin Hall metals or topological insulators using nonmagnetic material(NM) /oxide/ferromagnet (FM) junctions and measuring the induced transverse voltage, we are able to study SHE in typical 5d transition metals and the spin momentum locking in topological insulators. For spin Hall effect metals, the magnitude of the spin Hall angle has been a highly controversial topic in previous studies. Results obtained from various techniques (such as non-local spin valves, spin pumping and spin Hall torque) can differ by more than an order of magnitude. With the spin polarized tunneling experiment, we determined the spin Hall angles for heavy element metals (e.g., Ta, Pt, Ir and W). These results turned out to be consistent with the numbers obtained from spin Hall torque measurements, which can help to address this long debating issue. Besides the magnitude, the mechanism of the observed spin Hall effect (or spin orbit torques) is another issue that has attracted a lot of research interests. Competing mechanisms (intrinsic vs extrinsic, surface vs bulk origin) have been proposed to explain the observed phenomena. The voltage dependent spectra from our experiment provide useful information in distinguishing between those potential mechanisms. Finally, because of the impedance matching capability of tunnel junctions, the spin polarized tunneling technique can also be used as a powerful tool to measure resistive materials such as the various newly discovered and proposed topological insulators. In this talk, the results on the typical topological insulator will be reported.

B-323

GB‐04

Spin-Orbit Torque Control of Magnetic Insulator with Perpendicular Magnetic Anisotropy

Chi-Feng Pai(a,b), Andy Quindeau(b), Astera S. Tang(b), Maxwell Mann(b), Lucas Caretta(b), Mehmet C. Onbasli(b), Caroline A. Ross(b), and

Geoffrey S. D. Beach(b)

(a)Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan

(b)Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America

e-mail: cfpai@ntu.edu.tw / cfpai@mit.edu

Spin Hall effect (SHE)-induced spin-orbit torque (SOT) has been shown to be an efficient mechanism to control the magnetization in magnetic heterostructures. Although numerous works have demonstrated the efficacy of SOT in manipulating the magnetization of ferromagnetic metals (FM), SOT-controlled switching of ferromagnetic insulators (FMIs) has not yet been observed. Here we show that spin Hall currents in Pt and Ta can generate SOTs strong enough to control the magnetization direction in an adjacent thulium iron garnet FMI film with perpendicular magnetic anisotropy (PMA). We find that dc current in the heavy metal (HM) generates an out-of-plane effective field in the FMI consistent with an anti-damping torque whose magnitude is comparable to that observed in all-metallic systems. Spin Hall magnetoresistance (SMR) measurements reveal a large spin-mixing conductance, which implies considerable spin transparency at the metal/insulator interface and explains the observed strong current-induced torque. Our results show that charge currents flowing in a HM can be used to both control and detect the magnetization direction in a FMI electrically.

Fig. 1 Typical anomalous Hall‐like spin Hall magnetoresistance (SMR) signals from a Pt/TmIG bilayer sample, indicating PMA in this material system.

B-324

GB‐05

Towards Novel Spintronic Materials Discovery by X-ray

Yuan-Chieh Tseng

Dept. of Materials Science & Engineering, National Chiao Tung University 1001 Ta Hsueh Road, Hsin-Chu, Taiwan 30010

In this talk I will present two studies as an example of taking advantage of x-ray techniques to investigate spintronic materials.

In first case we demonstrate the use of x-ray technique to explore the phase-driven magneto-electrical characteristics of single layer MoS2. X-ray helped us understand the mechanism that controls the 1T magnetic phase over the MoS2 2D landscape. It also proved the strong coupling between electrical performance and the tunable magnetic phase of the MoS2 field effect transistors. By engineering the 1T phase properly the MoS2 FET became versatile which performed as a rectify diode generating linear and saturated electrical signals. This proves the feasibility of spin creation and manipulation in MoS2.

In second case we report an investigation of the physical principles regulating the tunneling magneto-resistance (TMR) and perpendicular magnetic anisotropy (PMA) of the CoFeB/MgO magnetic tunnel junction (MTJ) by means of angle-resolved x-ray magnetic spectroscopy. This x-ray technique provided greater sensitivity to symmetry-related d-band occupation compared to traditional x-ray spectroscopy. This added degree of freedom successfully solved the unclear mechanism of this MTJ system renowned for controllable PMA and excellent TMR. As a surprising discovery, these two physical characteristics interact in a competing manner because of opposite band-filling preference in space-correlated symmetry of the 3d-orbital. This important finding reveals that simultaneously achieving fast switching and a high tunneling efficiency at an ultimate level is improbable for this MTJ system owing to its fundamental limit in physics.

B-325

GB‐06

Enhanced current-perpendicular-to-plane giant magnetoresistance effect in half-metallic NiMnSb

Heusler alloy based nano-junctions with multiple Ag spacers

Zhenchao Wen, Takahide Kubota, Tatsuya Yamamoto, and Koki Takanashi

Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

e-mail: Wen.Zhenchao@imr.tohoku.ac.jp

Well-designed magnetic heterostructures with novel materials exhibiting large magnetoresistance effect are indispensable for advanced spintronic applications. Current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) heterostructure devices have been attracting great interest because of potential applications for next generation hard disk drives (HDDs) and all-metallic spin torque oscillators (STOs). Half-metallic Heusler alloys are promising materials for increasing the CPP-GMR effect due to their high spin polarization.

In this work, we fabricated single-, dual- and triple-Ag-spacer CPP-GMR devices combining with half-metallic NiMnSb Heusler alloy [1-2] electrodes. Fully (001)-epitaxial growth of NiMnSb half-Heusler alloy films and Ag layers were demonstrated in the single-, dual-, and triple-spacer CPP-GMR multilayer structures. A dramatically enhanced CPP-GMR effect was achieved in the dual-spacer devices. The CPP-GMR ratio shows an around double increase in dual-spacer CPP-GMR devices at room temperature (RT) compared to that in single-spacer ones. Meanwhile, a tripling enhancement of resistance-change area product (ΔRA) in the dual-spacer samples was also observed. The enhancement of CPP-GMR effect in dual-spacer devices could be attributed to the improved interfacial spin asymmetry. No further increase in CPP-GMR ratio was observed in the triple-spacer device, which could be due to the spin flip scattering at the increased layers, and/or the degraded quality of the upper layers as well as interfaces. The measuring temperature dependence of CPP-GMR effect shows a monotonic increase with decreasing the temperature. At 4.2 K, a maximum CPP-GMR ratio of 41% (ΔRA = 10.5 mΩμm2) was achieved in the dual-spacer CPP-GMR device. This work indicates that multi-spacer structures are efficient to enhance CPP-GMR effect in half-metallic material based CPP-GMR systems. [1] Z. C. Wen, T. Kubota, T. Yamamoto, and K. Takanashi, Sci. Rep. 5, 18387 (2015). [2] B. Kwon, Y. Sakuraba, H. Sukegawa, S. Li, G. Qu, T. Furubayashi, and K. Hono,

J. Appl. Phys. 119, 023902 (2016).

B-326

GB‐07

Noncollinear magnetization between Surface and Bulk Y3Fe5O12

Po-HsunWu and Ssu-Yen Huang

Department of Physics, National Taiwan University, Taipei, Taiwan

e-mail: r03222065@ntu.edu.tw e-mail: syhuang@phys.ntu.edu.tw

YIG (yttrium iron garnet, Y3Fe5O12) is a magnetic insulator, which has been widely used to drive spin current by longitudinal spin Seebeck effect (LSSE). The spin current can be converted to charge current in Pt layer via inverse spin Hall effect(ISHE) due to spin orbit coupling, where the spin polarization direction of the spin current is determined by the magnetization orientation of underlying YIG. However, the ISHE voltage induced from thermal transport of LSSE and the magnetoresistance measured from electric transport in Pt/YIG-slab have been found inconsistent with the field dependent magnetization of YIG in the low field range. In this work, with the magneto-optic Kerr effect (MOKE) measurement, we provide direct evidence to demonstrate the noncollinear magnetization behavior between bulk and surface YIG contributes to the plateau phenomenon. We further show that the surface magnetization of YIG can be systematically controlled by varying the bulk thickness with the same measured surface in one sample. The plateau feature can even exist by inserting the thick normal metal and insulator layers, indicating a robust magnetic dipole-dipole interaction between YIG and ferromagnet.

B-327

GC-01

Ferromagnetism at the Surface of Antiferromagnet

Induced by the Exchange Coupling in the Nanogranular

Layer

Jung-Il Hong, Min-Seung Jung

Department of Emerging Materials Science and DGIST Center for Emerging Materials,

DGIST, Daegu 42988, Korea

The atoms around the interface between ferromagnet and antiferromagnet are

under the influence of exchange interactions among the atoms on both ferromagnetic

(FM) and antiferromagnetic (AFM) sides, hence the spin arrangements at the interface

is often expected to be different from the single FM or AFM phases. With the

formation of nanoscale granular film consisting of FM and AFM phase mixture,

interface area is maximized and the distorted spin arrangement around the interface

area is expected to affect the saturation magnetization measured as a function of

temperature. FM Co0.7Ni0.3/ AFM Co0.7Ni0.3O films were sputter deposited with

various metal to oxide ratio to achieve various interface densities in the film, and we

report that the saturation magnetization increases with temperature as opposed to the

usual expectations for normal magnetic materials. The interesting behavior is

interpreted to be the result of the spin behaviors on the AFM side of the interface,

which follows the behavior of neighboring ferromagnet. It is thought that the magnetic

moment are released from the antiferromagnetic ordering and they act as coupled to the

neighboring ferromagnetic moments.

B-328

GC-02

All-optical manipulation of magnetization and ultrafast non-local spin dynamics

Arata Tsukamoto (a)

(a) College of Science and Technology, Nihon University, Funabashi, Chiba, JAPAN e-mail: atsuka@ecs.cst.nihon-u.ac.jp

Ultrafast control of magnetization is crucial for future applications on magnetic and spintronic devices. Controlling magnetism by light is one of the promising approaches as appealing scenario. For optical manipulation of magnetization, femtosecond laser pulses that are among the shortest stimuli in contemporary technologies could serve as an alternative stimulus to trigger magnetization reversal.

An ultrashort laser pulse allows excitation of magnetic systems at time scales much shorter than fundamental quantities such as spin precession or spin-lattice relaxation times. Deterministic magnetization reversal was demonstrated[1][2] in ferrimagnetic GdFeCo driven by single shot irradiation of laser pulse without the presence of a magnetic field. This All Optical Switching (AOS) phenomena originated from transient non-equilibrium state and sub-lattice nature is fundamentally different from conventional magnetic field driven switching mechanism.

Recently, it is revealed that further extraordinary spin dynamics in ultrashort time scale such as bellow ps region by ultrafast diffraction experiments with an X-ray probing[3]. In particular, we observed Gd spin reversal in Gd-rich nano-regions within the first picosecond driven by the non-local transfer of angular momentum. These results suggest that a magnetic microstructure can be engineered to control transient laser-excited spins, potentially allowing faster spin reversal. Furthermore, the energy dissipation to depth direction within few tens nm thick film is affect to the triggering AOS[4]. Ultrashort non-local phenomena in magnetic material will be discussed. It will be also shown that employing plasmonic gold nano-antennas placed above TbFeCo magnetic layer it should be possible to confine opto-magnetic excitation in a spot well below diffraction limit as the order of 50 nm[5].

Acknowledgment: This work was partially supported by MEXT-Supported Program for the Strategic Research Foundation at Private Universities, 2013-2017 and Grant-in-Aid for Scientific Research on Innovative Area, “Nano Spin Conversion Science” (Grant No. 26103004).

References: [1] T. A. Ostler, et. al., Nature Comm., 3, 666 (2012). [2] C. D. Stanciu, F. Hansteen, A. V. Kimel, A. Kirilyuk, A. Tsukamoto, A. Itoh, and Th.

Rasing, Phys. Rev. Lett., 99, 047601 (2007). [3] C. E. Graves et. al., Nature Materials 12, 293 (2013). [4] H. Yoshikawa, S. Kogure, T. Sato, A. Tsukamoto, and A. Itoh, J. Magn. Soc. Jpn., 3

(2), 139 (2014). [5] T. Liu et. al., Nano Letters, 15 (10), 6862 (2015).

B-329

GC-03

Synchrotron X-ray Scanning Tunneling Microscopy: A Novel Approach for the Nanoscale Characterization of Functional

Magnetic Materials with Chemical Contrast

Volker Rose

X-ray Science Division & Center for Nanoscale Materials Argonne National Laboratory

9700 South Cass Avenue Argonne, IL 60439-4800 United States of America

Adj. Professor Physics & Astronomy Department

Ohio University, Athens, OH 45701, USA

The real-space observation of magnetic structure using scanning probe microscopy (SPM) methods or synchrotron-based microscopy continues to have a tremendous impact on our understanding of functional magnetic materials. However, although SPM methods provide high spatial resolution, they lack direct chemical contrast and the ability to quantify magnetic moments. X-ray microscopy, on the other hand, can provide chemical as well as magnetic sensitivity, but the spatial resolution is limited.

In order to overcome these limitations, we have developed a new technique1 that combines synchrotron radiation with the high spatial resolution of scanning tunneling microscopy (STM). The goal is to combine the spin sensitivity of x-ray magnetic circular dichroism (XMCD) with the locality of STM. Synchrotron x-ray scanning tunneling microscopy (SX-STM) demonstrated the capability to obtain elemental contrast with a lateral spatial resolution of only 2 nm and sensitivity at the limit of single-atomic height.2 Recently, we achieved the first measurements of the local XMCD signal of magnetic domains in a Fe film using a non-magnetic-tip that is actually tunneling over the surface.3 The achievement of localized spectroscopy with simultaneous topographic, elemental, and magnetic information has the potential to significantly impact characterization of complex materials at the nanoscale.

In this talk we will review the recent developments and achievements in the field of SX-STM, with emphasis on its impact for the advanced characterization of functional magnetic materials. Particularly, the emerging opportunities gained by the world’s first low-temperature SX-STM, currently under commissioning at the Advanced Photon Source, will be discussed.

This work was funded by the Office of Science Early Career Research Program through the Division of Scientific User Facilities, Office of Basic Energy Sciences of the U.S. Department of Energy through Grant SC70705. This work was performed at the Advanced Photon Source and the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility under Contract No. DE-AC02-06CH11357.

References: 1 V. Rose, J.W. Freeland, S.K. Streiffer, "New Capabilities at the Interface of X-rays and Scanning Tunneling Microscopy", in Scanning Probe Microscopy of Functional Materials: Nanoscale Imaging and Spectroscopy, S.V. Kalinin, A. Gruverman, (Eds.), Springer, New York, pg 405-432 (2011). 2 Nozomi Shirato, Marvin Cummings, Heath Kersell, Yang Li, Benjamin Stripe, Daniel Rosenmann, Saw-Wai Hla, and Volker Rose, Nano Lett. 14, 6499 (2014). 3 Andrew DiLullo, Nozomi Shirato, Marvin Cummings, Heath Kersell, Hao Chang, Daniel Rosenmann, Dean Miller, John Freeland, Saw-Wai Hla, and Volker Rose, J. Synchrotron Rad., in print (2016).

Contact: vrose@anl.gov

Webpage: www1.aps.anl.gov/SXSPM

B-330

GC-04

When ferromagnetic metals meet organics -- A synchrotron investigation of hybrid organic spin-valve

D. H. Wei , K. T. Lu, C. I. Lu, T. H. Chuang, Y. J. Hsu National Synchrotron Radiation Research Center, Hsinchu, Taiwan

Transporting spins through carbon-based devices is one promising development in spintronics. By integrating ferromagnetic (FM) electrodes with an organic semiconductor (OSC) spacer, hybrid structures were thought to expand spin manipulation into applications that are hard to be realized with solid-state devices. However, the adoption of OSCs has brought in concerns as well. For example, the direct contact of soft organic spacer and hard metallic electrode raises the issue on the wellness of interfaces, and what impacts would an ill-defined interface brought to transport behaviour. In this presentation, I will briefly address the challenges faced in hybrid structure, followed with an introduction describing how synchrotron X-ray spectroscopy can help to provide insights that are hard to obtain otherwise. Three series of samples; Fe/C60, Co/C60, and Ni/C60, were prepared and examined at BL05B2, Taiwan Light Source. Utilizing synchrotron’s penetration power and element selectivity, we found all three series of interface bear clear signatures of orbital hybridization. Moreover, the X-ray absorption spectra recorded in electron emission mode revealed unexpected variations in both spectral resonances and intensities as a function of C60 thickness. An empirical model is proposed to rationalize the experimental finding. Conclusions drawn from the model analysis are discussed along with selected transport measurements reported earlier.

Figure 2: The corresponding ordered pattern of the two types of bonds for the three types of antiferromagnetic and structural orders in Figure 1 [10]. (b) refers to the commensurate limit of the 11 magnetic order in Fig. 1.

Figure 1: The antiferromagnetic structures of NdFeAsO(1111) [1], FeTe (11) [3] and K2Fe4Se5 (245) [4]. The antiferromagnetic bond is expanded and the ferromagnetic bond is contracted in all three types of structural and magnetic transitions [8].

B-331

GC-05

Investigation of multiferroic Bi(Pb)FeO3/SrRuO3/SrTiO3

heterostructure by Rutherford backscattering Murtaza Bohra(a), K. Negi(a), Varun Karthik Y.S.(a), H. Chou(b), X. Wang(c)

and W-K Chu(c)

(a)Mahindra Ecole Centrale, Hyderabad, India, (b)National Sun Yat-Sen University,

Kaohsiung, Taiwan, (c)Texas Center of Superconductivity, University of Houston, USA. e-mail: hchou@mail.nsysu.edu.tw

Bi(Pb)FeO3/SrRuO3/SrTiO3 hetero-structures fabricated at different Bi(Pb)FeO3

temperature (Tg) exhibit strain relaxation (reciprocal space maps: Fig. a) at each interface and eventually two Bi(Pb)FeO3 peaks. Rutherford backscattering (RBS) was employed to understand this unusual behavior, whether its mixture of two phases, layer splitting or inter-diffusion of elements. RBS ratio (min: 34 to 100%) of aligned and random spectra near surface regions (Fig. b) of Bi(Pb)FeO3 layers indicate degradation of crystalline quality with Tg. Fitting of RBS data of SrRuO3 layer suggest significant Ru vacancies at Bi(Pb)FeO3/SrRuO3 interface compared to the SrRuO3/SrTiO3 interface, which also contributes in the strain relaxation process. Surprisingly, at high Tg = 700°C, no difference between random and aligned spectra is observed, indicating presence of large amount of defects/distortions and lattice misfit at interface. The RBS composition analysis give clear evidence of inter-diffusion of Pb and Bi elements deep into SrRuO3/SrTiO3 interface, which causes two RSM peaks of Bi(Pb)FeO3 and Sr(Bi,Pb)TiO3. Below Tc

SrRuO3, the magnetic properties of Bi(Pb)FeO3/SrRuO3/SrTiO3

hetero-structures are also greatly altered with Tg and detail will be discussed.

Figure 1. Reciprocal space maps (a) and Rutherford backscttering spectrums (b) at different Tg.

B-332

GC-06

Large magnetocaloric effect in Ni-Mn-Ga-Cu ferromagnetic shape memory alloys

Dewei Zhao(a), Jian Liu(a)

(a)Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China

e-mail: liujian@nimte.ac. cn

Recently, magnetic refrigeration as an alternative to conventional vapor compression

cooling has received much concern. Magnetocaloric effect (MCE) is the origin of magnetic refrigeration and it can be characterized by isothermal entropy change ΔS. Ni-Mn-(In,Sn,Sb) metamagnetic shape memory alloys have been proposed as refrigerants in MCE since they display inverse and giant MCE in the vicinity of the martensitic transition temperature [1]. However, in these alloys, the contributions of lattice subsystem and magnetic subsystem play against each other to the total ΔS [2]. This is one of obstacles for Ni-Mn-based alloys for applications.

In this work, the martensitic transition and MCE in Ni50CuxMn25-xGa25(x=5.5, 6, 6.5) polycrystalline alloys were investigated. It can be seen in Fig. 1 (a) that for the higher content of Cu, the coupled magnetostructural transition becomes more pronounced. It is interesting to find in Fig. 1 (b) that in a magnetic field of 50 kOe, a complete magnetic-field-induced forward martensitic transition is observed in these alloys. Both thermal and magnetic field induced martensitic transition hysteresis are relatively small. Magnetic entropy changes ΔSm for Ni50CuxMn25-xGa25(x=5.5, 6, 6.5) alloys are 12.0, 15.5 and 16.5 J kg-1 K-1 in the magnetic field of 50 kOe, respectively, as shown in Fig. 1 (c). The enhanced magnetocaloric properties might be ascribed to the positively coupled contributions of lattice and magnetic subsystems.

Figure 1 (a) Magnetization versus temperature curves for Ni50CuxMn25-xGa25 in 500 Oe upon heating and cooling. (b) Magnetization curves at selected temperatures. (c) ΔSm

versus temperature curves in 50 kOe [1] A. Planes, L. Mañosa, and M. Acet.J. Phys.: Condens. Matter 21 (2009) 233201. [2] J. Liu, T. Gottschall, K. P. Skokov, J. D. Moore and O. Gutfleisch. Nature Materials 11 (2012) 620.

B-333

PS-01

Termination Effect of LSMO on Interfacial Electronic and Magnetic Properties in Alq3-based Organic

Spintronics

Tu-Ngoc Lam(a), Ming-Wei Lin(b), Yu-Ling Lai(b), Hong-Ji Lin(b), Ying-Hao Chu(c), Yao-Jane Hsu*(b),(d)

(a) Institute of Nanotechnology, National Chiao Tung University, Hsinchu, Taiwan

(b) National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan (c)Department of Materials Science and Engineering, National Chiao Tung

University, Hsinchu, Taiwan (d) Department of Photonics, National Cheng Kung University, Tainan, 70101,

Taiwan e-mail: yjhsu@nsrrc.org.tw

The interfacial regions at organic-ferromagnetic hybrid structures are critical to affect the spin injection and transport in organic spin valves (OSVs) since spin-polarized charge carriers across these interfaces. Understanding the interfacial behavers at FM-OSC-FM heterostructures is crucial for the design and operation of OSV devices. Herein, we investigated influence of different termination layers of lanthanum strontium manganite (LSMO) on the interfacial electronic and magnetic properties of LSMO/Alq3 heterostructures. Different termination layers of LSMO with LSO, MnO2 and mixed terminations were prepared to examine the spin interface of LSMO/Alq3. From experimental results, the outermost layer of LSO and mixed terminations exhibited significant SrO segregation while less segregation was found for MnO2. In addition, the surface SrO segregation correlates to the variation of surface magnetic properties and the formation of surface dipole at the mixed LMSO/Alq3, MnO2-ter/Alq3, and LSO-ter/Alq3 interfaces.

Fig.1 XMCD spectra of LSMO with MnO2 termination before and after Alq3 adsorption.

[1] Y. Q. Zhan, I. Bergenti, L. E. Hueso, and V. Dediu, Phys. Rev. B 76, 045406 (2007).

B-334

PS-02

Voltage induced reversible and irreversible change of magnetic coercivity in Co/ZnO heterostructure

Chuan-Che Hsu , Po-Chun Chang ,

Venkata Ramana Mudinepalli, Tsung-Chun Hsieh, Fang-Yuh Lo , and Wen-Chin Lin

Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan

In this study, the application of bias voltage to 4–8nm Co/275nm ZnO

heterostructures changed the magnetic behavior reversibly or irreversibly, depending

on the different voltage-induced mechanisms. The magnetic coercivity (Hc)

monotonically decreased 20% when the small voltages of 0–8V were applied. The Hc

reduction was symmetric with the voltage polarity, and the reversibility was

demon-strated by cyclically switching the bias voltage between 0 and 7V. While a

large voltage up to 40V was applied to the Co/ZnO junction, the current heating effect

became considerable and the Co-oxide was formed, as confirmed by depth-profiling

X-ray photoemission spectroscopy analysis. The pres-ence of Co-oxide in the Co films

induced the irreversible reduction of the Kerr signal and Hc at room temperature. The

considerable Hc enhancement at 130K also indicates the exchange bias coupling effect

from the antiferromagnetic Co-oxide.

B-335

PS-03

Modulating magnetic anisotropy by stress/strain in flexible magnetic thin films

Baomin Wang(a),(b), Yiwei Liu(a), (b), Qingfeng Zhan(a), (b), and

Run-Wei Li(a), (b) (a)Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials

Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China

(b)Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of

Sciences, Ningbo 315201, China Recently, flexible electronics have attracted wide attention due to the advantages

of flexibility, wearable, and low fabrication cost etc. Magnetic materials are important components to fabricate the electronic devices. Magnetic anisotropy of magnetic materials not only determines the moment orientation and coercivity but also affects the operation frequency and even power consumption of a magnetic device. Therefore, the preparation of flexible magnetic thin films and the modulating of their magnetic anisotropy by extra fields are very helpful for developments of flexible magnetoelectronic devices.

By depositing magnetostrictive metals (such as FeGa, CoFeB etc) on flexible substrate, we found effective tuning of the magnetic anisotropy by applying stress/strain. The magnetic films exhibit an obvious in-plane uniaxial magnetic anisotropy which could be enhanced by increasing the applied pre-strains on the substrates during growth. Consequently, the ferromagnetic resonance frequency of the films was significantly increased. Furthermore, we utilized the anisotropic thermal expansion of PVDF, combined with the magnetoelastic anisotropy of magnetic materials to design a class of magnetic composites with positive temperature coefficient of magnetic anisotropy. In the meanwhile, by utilizing the ferroelectricity and anisotropic thermal expansion of PVDF, an effective tuning of the magnetic anisotropy and magnetization orientation can be realized by external multi-fields.

Relating works have been published in Appl. Phys. Lett. 100, 122407 (2012), Appl. Phys. Lett. 102, 022412 (2013), J. Appl. Phys. 113, 17A901 (2013), J. Appl. Phys. 113, 17C705 (2013), J. Appl. Phys. 114, 173913 (2013), Chin. Phys. B. 22, 127502 (2013) (invited review), Appl. Phys. Lett.105, 103504 (2014), Sci. Rep. 4, 6615 (2014), Sci. Rep. 4, 6925 (2014), Appl. Phys. Lett 106, 162405 (2015), AIP Adv. (in press). These studies were supported by NSFC, 973 Project, and projects from Zhejiang province and Ningbo city.

B-336

PS-04

Annealing-induced alloy formation in Pd/Fe bilayers on Si(1 1 1) for hydrogen sensing

Venkata Ramana Mudinepalli(a),*, Cheng-Jui Tsai(a), Ying-Chin Chuang(a), Po-Chun Chang(a), N. Plusnin(b), Wen-Chin Lin(a)

(a)Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan. (b)Institute of Automation and Control Processes, 5 Radio Str., Vladivostok, Russia.

e-mail: ramana6slrpdf@gmail.com

The bilayers of Pd and Fe with different thickness and relative positions were

grown on Si(1 1 1)-7 × 7 surface at room temperature. For the investigation of the

thermal annealing induced inter-diffusion and the corresponding magnetic behavior,

Auger electron spectroscopy (AES) measurement was carried out after various

annealing processes, including the variation of annealing duration and temperature.

With the annealing temperature of 300–500K, the Pd/Fe bilayers were stable. Slight Si

segregated into the thin film at around 700K. Above 700K, more serious Si segregation

occurred and most of the Pd/Fe bilayer was mixed with Si, forming a silicide layer.

700–800K annealing also induced change of Pd/Fe AES ratio, indicating the

inter-diffusion between Pd and Fe layers. To overcome the unavoidable silicide

formation induced magnetic dead layer, a relative thick Fe film of 20 ML capped with

1.5 ML Pd was chosen for the investigation of magnetism. The magnetic coercivity

(Hc) increased by 2–3 times with the annealing temperature up to 740K. Obvious

hydrogenation effect was observed in 710K-annealed sample; the inplane Hc increased

by more than 10% when the hydrogen pressure was above 200 mbar. After further

annealing at 740–800K, the hydrogenation effect on Hc became nearly unobservable.

The annealing induced Pd-rich magnetic interface is supposed to dominate the

hydrogenation effect on magnetism.

B-337

PS-05

Effects of Fe content on the magnetic properties and microstructure of Pr-Fe-B thin films

Ching-Fong Shea, Yu-Shen Chen, and An-Cheng Sun

Department of Chemical Engineering and Material Science, Yuan-Ze University, Chung-Li, Taoyuan, Taiwan

e-mail: acsun1976@gmail.com

Nd-Fe-B magnetic thin films have been regarded as the potential applications in

the permanent magnet and micro-electro-mechanical systems (MEMS) because their

outstanding magnetic performances [1]. However, the magnetic properties would be

deteriorated at 150 K due to the spin reorientation of the hard Nd2Fe14B phase.

Therefore, Pr-Fe-B thin film will substitute Nd-Fe-B thin film owing to its very low

spin reorientation temperature (~4.2 K) [2]. However, rare reports investigate about the

relation between chemical composition, microstructures, and magnetic properties. In

this study, the effect of composition ratio of Pr to Fe on magnetic properties and

microstructure would be discussed.

Our results observed that the Ms increase with increasing the Fe content, and

coercivity (Hc) increase to the maximum value and then decrease. XRD results showed

the low Hc is due to the less hard Pr2Fe14B phase. The meta-stable phase Pr2Fe23B3

declined Hc in higher Fe content samples. From the EDS analysis, it was found that the

Fe in PrFeB thin film diffused into Si3N4 underlayer, forming Pr-rich phase in the

PrFeB layer. It is clear that the Hc was influenced by the Pr-rich and PrFeB distribution.

The maximum Hc appears at Fe=75.53 at.% and the highest PMA was obtained at

Fe=72.18 at.%. In this study, the high magnetic properties may exist when Fe

composition is from 72 to 75 at.%. The details of mechanism that influence magnetic

properties will be discussed in this article.

Keywords: PrFeB; Thin film; Magnetic properties; Fe content

[1] D. Weller, A. Moser, L. Folks, M. E. Best, W. Lee, M. F. Toney, M. Schwickert, J. U.

Thiele, and M. F. Doerner, IEEE Trans. Magn. 36, 10 (2000).

[2] C. Abache, and H. Oesterreicher. J. Appl. Phys. 57, 4112 (1985).

B-338

PS-06

Voltage-controlled in the magnetic exchange coupling of Fe /ZnO/Zn1-xFexO heterostructures

Po-Chun Chang, Fang-Yu Lo, Wen-Chin Lin*

Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan

*e-mail : wclin@ntnu.edu.tw

The metal/oxide hetero-structure has attracted much attention in recent decades because of its potential in various applications such as heterogeneous catalysis and electric-field controlled magnetism. In particular, the combination of magnetic metal with an oxide thin film (e.g., a magneto-tunneling junction) has been widely studied and applied in data storage and spintronics. ZnO is one of the important semiconducting materials, not only for photoluminescence but also more importantly for its promising applications in spintronics. Transition metal-doped ZnO is predicted to be useful as a magnetic semiconductor for room-temperature application. Furthermore, ZnO exhibits the largest electromechanical response, among the known tetrahedral semiconductors, which makes it suitable for devices in microelectromechanical and communication systems.

In our experiment, we used e-beam evaporation to grow Fe films and used pulsed laser deposition to deposit ZnO doped with Fe and on Al2O3 (0001). The magnetic property was investigated by magneto optical Kerr effect in in-plane directions.

The hysteresis loops of Fe/ZnO/Zn1-xFexO heterostructures revealed two

switching field. The coercivity of the two switching field depended on the thick of Fe film and decreased when an electric field was applied. Reference 1. C. C. Hsu, P. C. Chang , C. J. Tsai, T. C. Hsieh, F. Y. Lo, W. C. Lin, submitted to J.

Appl. Phys. (2015).

2. W. C. Lin, P. C. Chang, C. J. Tsai, T. C. Shieh, and F. Y. Lo, Appl. Phys. Lett. 104,

062411 (2014).

3. W. C. Lin, P. C. Chang, C. J. Tsai, T. C. Hsieh, and F. Y. Lo, Appl. Phys. Lett. 103,

212405 (2013).

B-339

PS-07

Magnetic properties and related structures for Co-rubrene composite films

Yong-Jhih Hou, Cheng-Hsun-Tony Chang, Chun-Kai Yang, Chih-Yu Hsu,

Yen-Wei Jhou, and Jyh-Shen Tsay*

Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan *jstsay@phy.ntnu.edu.tw

Because of the potential uses of low-cost and flexible-substrate-based

electronics, semiconducting organic materials have attracted much attention in the past

decade. In this contribution, structures and magnetic properties of Co-rubrene

composite films on Si(100) have been studied by employing atomic force microscopy

(AFM) and magneto-optic Kerr effect techniques. For composite films prepared by

co-depositions of Co and rubrene on Si(100), the surface is smooth while a layered

distribution of Co atoms is detected. For very thin CoRub0.33 films, the surface is

smooth while some small bumps with an average diameter around 150 nm appear.

More defect sites in the film are the main reason of the observation of larger coercive

force. For thicker CoRub0.33 films, the small bumps disappear and the surface is

smoother. Rubrene molecules play the role as a surfactant and can efficiently reduce

the interaction at the film/Si interface. By increasing the rubrene concentration, more

Co/rebrene interfaces are introduced in the composite films and the more rubrene

served as a surfactant enhances the quality of the films. These information are valuable

for future applications combining organic semiconductor and spintronics.

B-340

PS-08

Fig. 1 Magnetic hysteresis loops measured at 180 K and 10 K

Exchange bias in NiFe/CoO/Fe2O3 trilayer

X. Li(a), Y.-C. Chang(b), W.-C. Yeh(b), K.-W. Lin(b), *, R. D. Desautels(c), J. van Lierop(c), *, P. W. T. Pong(a), *

(a)Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong.

(b)Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan

(c)Department of Physics and Astronomy, University of Manitoba, Winnipeg, R3T2N2, Canada

*e-mail: kwlin@dragon.nchu.edu.tw; johan@physics.umanitoba.ca; ppong@eee.hku.hk

The magnetic properties of magnetic trilayer structures are influenced by both the

interfacial exchange coupling and the interlayer exchange coupling (IEC). Our previous results have shown strong IEC between ferromagnetic (FM) NiFe and Co through 12-nm-thick antiferromagnetic (AF) CoO spacer in FM1/AF/FM2 trilayer [1]. This has inspired us to further explore whether IEC between FM and AF2 also exists in FM/AF1/AF2 trilayer. α-Fe2O3 has AF coupling below 948 K. Large exchange bias (Hex) is observed in α-Fe2O3/NiO nanocomposite, while the exchange coupling in α-Fe2O3/AF is not well understood [2]. In this work, the magnetic properties of NiFe/CoO/Fe2O3 trilayers are comparatively studied with NiFe/CoO and NiFe/Fe2O3 bilayers to investigate the exchange coupling in FM/AF1/AF2 geometry and to explore the mechanism of α-Fe2O3/AF interaction.

The samples are prepared by dual ion-beam sputtering. Rock-salt CoO and rhombohedral α-Fe2O3 are formed, as characterized by selected area electron diffraction. The shifted but symmetric hysteresis loops indicate the absence of IEC. At 300 K, the samples exhibit small coercivity (Hc). After field cooling to 180K, enhanced Hc and Hex is observed in NiFe/CoO as CoO transforms into AF (Fig. 1a). The smaller Hex and Hc in trilayer is attributed to the exchange coupling in CoO/Fe2O3. The Morin transition in Fe2O3 is responsible for the enhanced Hex and Hc in NiFe/Fe2O3 at 10 K (Fig. 1b). This also results in vanished CoO/Fe2O3 exchange interaction and the same Hex and Hc in trilayer and NiFe/CoO. The DC magnetometry reveals lower irreversibility temperature in trilayer than in NiFe/CoO. This work shows the magnetic properties of FM/AF/Fe2O3 trilayer can be tailored by the phase transition in Fe2O3. [1]K.-W. Lin, T.-C. Lan, C. Shueh, E. Skoropata, and J. van Lierop, J. Appl. Phys. 115, 17D717 (2014). [2]X. H. Liu, W. B. Cui, X. K. Lv, W. Liu, X. G. Zhao, D. Li, and Z. D. Zhang, J. Appl. Phys. 103, 103906 (2008).

B-341

PS-09

Chirality dependent vortex annihilation in asymmetric permalloy dots

Deng-Shiang Shiu(a), Kuo-Ming Wu(a), Chao-Hsien Huang(a), Kao-Fan Lai(a), Jong-Ching Wu(a), and Lance Horng(a)

(a)Department of Physics, National Changhua University of Education, Changhua

500, Taiwan e-mail: phlhorng@cc.ncue.edu.tw

Here, we study the asymmetry effect on magnetic dots to control magnetic domain in order to employ them in magnetic sensors and logic devices [1]. Therefore, we fabricate samples in the form of series of submicron-scaled permalloy (Py) dots by e-beam lithography and magnetron-sputtering to investigate the geometrical asymmetry effects on vortex annihilation in the devices. By introducing an one-side-flat asymmetric shape into the circular magnetic disks [2], the original degenerate signals of vortex annihilation for different chiralities are separated into two different trajectories, where asymmetry level is quantified by an excised angle, as shown in Fig. 1. The separation of annihilation fields for clockwise and counter-clockwise vortexes emerges as a function of the excised angle. The asymmetric influence on the separation of annihilation fields is discussed from the view of disk aspect ratio and flat boundary effect. In order to make comparison of experimental results with numerical simulations, we employ micromagnetic simulation software - Object Oriented MicroMagnetic Framework (OOMMF) to model the behaviour of the domain states. We will employ this result of simulation to examine the variation of magnetic energies for different domain states. [1] Huang C H, Wu K M, Wu J C and Horng, J. Appl. Phys. 113, 103905 (2013) [2] Schneider M, Hoffmann H and Zweck J, Appl. Phys. Lett. 79, 3113 (2001)

Fig. 1 The definition of excised angle.

B-342

PS-10

Magnetic Properties of the NiFe Films Grown on the

Ferroelectric BiFeO3 layer

Chen-Hsu Chang, Yao-Sheng Hsu, Zheng-Wei Lin, Chin-Chung Yu

(a) Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan

e-mail: sunshineynorainy@gmail.com

Recently, BiFeO3 multiferroic films have been studied intensively due to its high electrical polarization that can be applied in the field of smart materials. In the field of spintronics, a ferroelectric layer can be used as a strain layer to modify the magnetic behavior of a nearby magnetic film. Moreover, the remanence polarization and strain can assist the maintenance of the magnetization state of the magnetic layer.

In this study, highly conductive Si substrates were used to deposit the BiFeO3/NiFe bilayers and the structural, ferroelectric, and ferromagnetic properties of the bilayers were investigated. The ploycrystal R-3C BiFeO3 films was obtained after a rapid thermal anneal under nitrogen ambient at 600oC for 5 mins. The coercivity and squareness of the BiFeO3 film were around 2V and 0.5, respectively. In the longitudinal MOKE measurements, unlike the ZnO/NiFe bilayers, the MOKE signal of the NiFe displayed a residual value as removing the applied voltage across the BiFeO3 layer. The modulation of the Kerr signal can be obtained under a low voltage ranged from 1 to 4V. For a higher applied voltage, a distortion of MOKE hysteresis was observed due to a large leakage current in the BiFeO3 layer. The correlation between the leakage behavior and the MOKE modulation will be presented.

B-343

PS-11

Studies on Magnetism of Transition Metal Layers Grown

on Graphene Chih-Heng Huang(a,b), Tzu-Hung Chuang(b), Chun-I Lu(b), Kun-Ta Lu(b),

Chien-Chen Kuo(a,c), Der-Hsin Wei(b)

aProgram for Synchrotron Radiation and Neutron Beam Applications, National Sun Yat-sen University, Kaohsiung, Taiwan

bNational Synchrotron Radiation Research Center, Hsinchu, Taiwan

cDepartment of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan

e-mail:windwalker129@gmail.com Magnetism of organic molecules and carbon atoms has attracted much attention. Among these materials, graphene, a single layer of carbon atoms, has been investigated intensively. Theoretical studies on transition metal induced magnetism of graphene has been developed for years[1][2], while growing such homogeneous thin film experimentally remains challenging. On the other hand, intercalation of cobalt through graphene has shown relatively strong ferromagnetism in cobalt, and anti-ferromagnetism in carbon, which is a candidate of layered magnetic material[3]. Here we report our studies on the magnetism of Fe, Co, or Ni thin film deposited on graphene. The graphene sheet was grown via chemical vapor deposition (CVD) on a Pt(111) substrate, which is known to have weak coupling with graphene[4] and form graphene without a certain orientation (Fig. 1). The magnetism was checked via MOKE and XMCD. The as-grown metal layers on graphene only showed in-plane magnetism at above 20ML (Fig. 2), and no significant magnetism of carbon was found. Sub-monolayer of Fe/Co/Ni intercalated under graphene remains for the future work. [1] Chao Cao et. al., Transition metal adatom and dimer adsorbed on graphene: Induced magnetization and electronic structures, Phys. Rev. B (81), 205424 (2010) [2] Yudistira Virgus et. al., Stability, Energetics, and Magnetic States of Cobalt Adatoms on Graphene, Phys. Rev. Lett. 113, 175502 (2014) [3] H. Vita et. al., Electronic structure and magnetic properties of cobalt intercalated in graphene on Ir(111), Phys. Rev. B 90, 165432 (2014) [4] Peter Sutter et. al., Graphene on Pt(111): Growth and substrate interaction, Phys. Rev. B 80, 245411 (2009)

Fig. 1 LEED image of CVD graphene

grown on Pt(111). K.E. =64eV. Fig. 2 XMCD of 25ML Co/G/Pt(111)

B-344

PS-12

Exchange coupling behaviour of the NiO/NiFe under

exertions of bias voltages

Li-Jing Wang, Zheng-Wei Lin, Chin-Chung Yu

Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan

e-mail: 91049lisa@gmail.com

The exchange coupling in the AFM/FM system is one of important phenomena in the

field of sensors and hard disk industry. The binary alloys with manganese, e.g. FeMn,

IrMn, PtMn, et al., are the common materials used for the AFM layer. The oxide

material, e.g. NiO, is also a good choice for the application. The NiO displays a p-type

semiconductive or a seminsulate behavior. Under an application of a bias voltage, the

cubic lattice will distort and display a small electric polarization. The change of the

spin lattice of the AFM layer and, consequently, the coupling on the AFM/FM interface

can be expected. The control of magnetic behavior through electrical voltage is more

accessible in the modern electronics than magnetic field. In this study, we focus on the

variation of the exchange field and coercivity of the NiO/NiFe system under bias

voltages.

The NiO layer was deposited on Si substrate by an RF sputtering. During deposition,

an in-situ magnetic field around 100 Oe was imposed on the Si substrate. The NiFe

films with different thickness were prepared on the NiO layer by thermal depositions.

The exchange field, Hex, and coercivity, Hc, of the NiO/NiFe(10nm) both displayed

values around 20 Oe. The both values of Hex and Hc were decreased as elevating the

bias voltage across the NiO layer. The change of the Hc value can be attributed to the

magnetostriction. The variation of the Hex may be due to the weakness of the exchange

coupling on the interface as the lattice distortion. Both of Hex and Hc can be modulated

under a voltage lower than 10V. The upper bound of the bias voltage, Vbound, was

controlled by the excitation processes of electrons inside the NiO layer. The correlation

between current leakage, Hex, Hc and Vbound will be discussed.

B-345

PS-13

Tunnel Magnetoresistance in MTJs with embedded nanoparticles according particle’s size distribution

A. Useinov(a,b,c), L.-X. Ye(b), N. Useinov(c), H.-H. Lin(a) and C.-H. Lai(b)

(a)Department of Physics, National Tsing Hua University (NTHU), Hsinchu, Taiwan (b)Department of Materials Science and Engineering, NTHU, Hsinchu, Taiwan

(c)Institute of Physics, Kazan Federal University, Kazan, Russian Federation e-mail: chlai@mx.nthu.edu.tw

The simulation is done for electron tunneling through the insulating layer of the magnetic tunnel junction with non-magnetic embedded nanoparticles (npMTJs). The distribution of the nanoparticles by size (DNPS) was important part of the solution for tunnel magnetoresistance (TMR) which was calculated on the basement of the double barrier tunneling model. It was found that theoretical agreement with experimental data can be influenced not only from DNPS but also due to different cases of the quantization. A few cases of the quantization related with a redistribution over quantum well (QW) states of the nanoparticles (NPs) (with diameter d) were considered (one of the possible DNPS and related TMR is shown in Fig.1a and Fig.1b). Numerous experimental works show a simple approach explaining TMR behavior in npMTJs [1, 2]. For example, the consecutive, Kondo-assisted cotunneling and Coulomb blockade models to explain the TMR anomalies in npMTJs was used, however the direct tunneling was neglected [1, 2]. In contrast to these studies, it was theoretically shown that quantized conductance regime in range of quantum-ballistic model (or direct tunneling) can be a real reason of anomalous TMR behaviors [3,4].

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

22

24

26

28

TM

R (

%)

Voltage (V)

(a)

1.0 1.5 2.0 2.5 3.00

10

20

30(b)

Co

n. (

%)

NP diameter (nm) Fig.1. (a) TMR at T = 2.5 K, QW states at n = 1, d < 1.7 nm and

n = 2 for d >1.7 nm; (b) NP distribution and concentration. [1] H. Yang, S. Yang and S.S.P. Parkin, Nano Lett., 8, 340 (2008). [2] D. Ciudad et. al, Phys. Rev. B, 85, 214408 (2012). [3] A. Useinov et al., Scientific Report, 5, 18026 (2015). [4] A. Useinov et al., IEEE Trans. Magn. 51, 4401404 (2015).

B-346

PS-14

Microstructure and magnetic properties of FePt/ (TiOC, TaC)/CrRu films

Jai-Lin Tsai, Jie-Lin Tzeng, Keng-Chun Hu, Hsu-Kang Li, Zu-Yu Pan, Yuan-Shuo Chang, Chang-Chun Liao

Department of Materials Science and Engineering, National Chung Hsing

University, Taichung 402, Taiwan e-mail: tsaijl@dragon.nchu.edu.tw

The ordered L10 FePt films are considered to be the heat assisted magnetic recording

media with area density above 1.5Tb/in2 due to high magnetocrystalline anisotropy

(Ku). Epitaxial growth of FePt films on MoC/CrRu/glass have been proved to promote

chemical ordering and [001] texturing and have perpendicular magnetization in our

previous work. In this study, TiOC, TaC, were used as the epitaxial intermediate layers

of FePt film. The Ta, Ti-carbide with near equal atomic ratio shows ground state NaCl

(face centered cubic) structure with a lattice constant larger than MgO (~0.42 nm). The

(200) textured MoC [1], TaC, and TiOC films with thickness of 25 nm were prepared

by direct current magnetron sputtering on CrRu(200)/[110]/glass at high temperature.

According to the x-ray diffraction patterns (XRD), the TaC (200) peak shows much

higher relative intensity than TiOC and the TaC (200) diffraction peak was shifted to

lower angle due to larger lattice constant than TiOC and MoC. The L10 FePt film was

deposited on TaC, TiOC intermediate layer at 425oC. The FePt films illustrate (001)

texture on TaC, TiOC intermediate layer with small ordering degree. It’s due to large

lattice misfit between TaC, TiOC and FePt. As a result, the FePt films show

perpendicular magnetization with large in plane hysteresis areas with TaC and TiOC

intermediate layer.

B-347

PS-15

Effect of DO3 phase on high frequency permeability of Fe-Si powder cores

Pyungwoo Jang(a), Gwangbo Choi(b)

(a)College of Sci. & Eng., Cheong University, Cheongju , Korea (b)Changsung Corp., Namdong Industrial Area, Incheon, Korea

e-mail: pwjang@cju.ac.kr

Fe-Si powder cores have been widely used in energy converting systems and others. In order to use the cores in a several megahertz, silicon content should much higher than that of well-known Fe-6.5% Si alloy. Fe-Si alloys with high silicon content consist of order DO3 and B2 phases as well as disordered A2 phase. However, the role of DO3 phase has been controversial in conjunction with good magnetic properties. Cooling rate of water quenched Fe-Si powders during gas-atomization is very high so that the evolution of the ordered phases from non-equilibrium phase changes microstructure and thus magnetic properties of the powder widely during annealing. However, the role of DO3 phase has been controversial and has not been reported in case of Fe-Si powder up to now. In this study Fe-Si powders with 7 – 11 wt.% Si were gas-atomized into cool water and then sieved to be of a mean diameter of 15 m. The sieved powders were annealed at Tanl = 25 - 750oC for 1 hour in nitrogen atmosphere and then packed into toroid capsules with insulating oil. Structure and magnetic properties were analysed with SEM, VSM, XRD and precision impedance analyser. (200) super lattice peak of B2 phase could be observed in all the as-atomized powders. Detection of (111) peaks of DO3 phase was possible in the powders annealed at Tanl higher than 550, 450 and 25oC in Fe-7, 9 and 11% Si powders, respectively as shown in Figure. Size of DO3 phase of Fe-7, 9%Si powder increased with Tanl while that of Fe-11%Si powder was almost unchanged. Hc of the Fe-Si powders decreased with increasing Tanl. However, there was an increase of Hc around evolution temperature of DO3 phase in Fe - 8, 9% Si powders. Permeability (’) of the Fe-7, 8, 9% Si powders at 10 MHz decreased with increasing Tanl while ’ of Fe-11% Si was almost constant. It was well reported that the electrical resistivity of the Fe-Si alloy changed very much depending on cooling rate in a Si content range of 8 - 20% Si [1]. The reason for the behaviour of Hc and ’ with Tanl seems to be due to change of electrical resistivity attributed from size increase of DO3 phase with Tanl. More experimental data and detailed discussion will be presented on the conference site.

[1] K. Numakura and etc, the 1557th report of the RIISOM, Tohoku university, 1972

Fig. 1 Size variation of DO3

phase of Fe-Si powder with Tanl

B-348

PS-16

The structures and magnetism of Fe/FeO/Fe/FeV characterized by magnetometry and polarized neutron

reflectometry

Sara J. Callori(a), (b)*, Kai-Han Chao(c), Béla Nagy(d), László F. Kiss(d), László Bottyan(d), Ko-Wei Lin(c), and Frank Klose(b),(e)

(a) Department of Physics, California State University, San Bernardino, CA 92407,

U.S.A (b) Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas

Heights, NSW 2234, Australia (c) Department of Materials Science and Engineering, National Chung Hsing

University, Taichung 402, Taiwan (d) Wigner Research Centre for Physics, H-1121 Budapest, Hungary

(e) Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China

e-mail: Sara.Callori@csusb.edu

The ferromagnet/metal Fe/V system displays interesting magnetic properties over

a wide range of temperatures, particularly with regards to induced magnetization near

the interface. Here, we use argon ion-bombardment during Fe layer deposition as a way

to tailor the structural and magnetic properties of bilayer and multilayer systems

containing Fe/FeV components. We present structural and magnetic results on Fe/FeV

bilayer and Fe/Fe-oxide/Fe/FeV multilayer systems. Transmission electron

microscopy and x-ray reflectivity measurements indicate a substantial amount of layer

mixing likely due to the ion- bombardment and show the formation of a layer with an

enhanced Fe concentration at the Fe/FeV interface. Magnetization measurements were

taken over a range of temperatures and show the expected ferromagnetic behaviour for

the Fe/FeV bilayer. The Fe/Fe-oxide/Fe/FeV multilayer demonstrates an enhanced

coercivity and exchange bias at low temperatures, both due to the presence of the

antiferromagnetic Fe-oxide layer. Polarized neutron reflectometry (PNR) [1] results

(scattering length density (SLD) depth profile and neutron spin asymmetry) are in

agreement with those measured by magnetometry and TEM. In this system, both

ferromagnetic Fe layers reverse simultaneously, indicating interfacial coupling which

may be mediated by the mixed Fe/Fe-oxide layers.

[1] W. Uilhoon et al., J. Phys. Conf. Series 711, 012005 (2016).

B-349

PT-01

Synthesis of cobalt-based carbide particles by polyol process and their magnetic properties S. Fujieda, A. Yomogida, K. Shinoda, S. Suzuki

Institute of Multidisciplinary Research for Advanced Materials, Tohoku

University, Sendai 980-8577, Japan

The metastable cobalt carbide with the Fe3C-type structure (Pnma) has attached much attention as a promising candidate for application to rare-earth free permanent magnets, because large magnetoanisotropy of Co3C has been predicted by the first-principal calculation [1]. The particles of Fe3C-type cobalt carbide have been synthesized by reduction of cobalt ions in polyol solution [2]. In this study, particles were synthesized at about 563 K for 30 min in tetraethyleneglycol (TEG) using chemicals such as Co acetate tetrahydrate, Ni acetate tetrahydrate and polyvinylpyrrolidone (PVP). The influence of both PVP and coexisting Ni ions on the precipitation of Fe3C-type cobalt carbide particles in polyol solution was examined. Figure 1 shows X-ray diffraction patterns of particles synthesized with and without PVP. When Co ions are reduced in solution without PVP, particles composed of fcc and hcp structures are precipitated. On the other hand, the diffraction peaks of particles synthesized in solution containing PVP are assigned primarily as the Fe3C-type structure. Therefore, the presence of PVP in TEG solution accelerates the formation of Fe3C-type cobalt carbide. The carbide particles exhibited a coercivity of about 1.7 kOe at room temperature. As shown in Fig. 1, particles synthesized in solution with the initial molar ratio of Co:Ni = 9:1 are also identified as the Fe3C-type structure. Their local structure around Ni atoms was investigated by a extended X-ray absorption fine structure (EXAFS) spectrum measurement. The result is shown in Fig. 2 (a). The shape of EXAFS spectrum of particles synthesized in solution containing Ni ions is similar to that of Co K edge of Fe3C-type cobalt carbide particles as indicated in Fig. 2 (b). Consequently, particles of Ni-substituted cobalt carbide with the Fe3C-type structure are obtained by controlling reduction conditions. [1] M. Qian et al., J. Appl. Phys. 114 (2013) 243909. [2] V. G. Harris et al., J. Phys. D: Appl. Phys. 43 (2010) 165003.

40 60 80 1002 (degree)

Inte

nsi

ty (

a.u.

)fcc Co (#15-0806)

With PVP, Co:Ni=9:1

hcp Co (#05-0727)

With PVP, Co:Ni=10:0

Without PVP, Co:Ni=10:0

Co3C (#26-0450)

20 40 60 80 100 120

k3 (k

) (a

.u.)

k (nm-1)

With PVP, Co:Ni = 10:0 (b)

Co K

k3 (k

) (a

.u.) With PVP, Co:Ni = 9:1 (a)

Ni K

Fig. 1 X-ray diffraction patterns of particles synthesized under various conditions

Fig. 2 Extended X-ray absorption fine structure (EXAFS) spectra of particles synthesized with Co:Ni = (a) 9:1 and (b) 10: 0

B-350

PT-02

Improving cell migration in wound healing using intracellular magnetic nanoparticles and magnetic force

Wan-Ying Huang, Chao-Ming Su, Shyh-Liang Lu, Tzong-Rong Ger

Department of Biomedical Engineering, University of Chung Yuan, Taoyuan, Taiwan e-mail: sunbow@cycu.org.tw

In this study, the ability for an applied external magnetic field to attract magnetic

nanoparticles which have been internalized within cells inducing cell to migrate in the direction of the field in wound healing are investigated. The preparation of the CM-Dextran/Fe3O4 magnetic nanoparticles was firstly synthesized by co-precipitation method. Followed by functionalization of Arginine-Glycine-Aspartic acid (RGD) peptide to modify the surface of CM-Dextran/Fe3O4 forming RGD/Dextran/Fe3O4 composite magnetic nanoparticles. Evidence of the RGD/Dextran/Fe3O4 composite magnetic nanoparticles via FT-IR detection, TEM and SQUID were studied.

The composite magnetic nanoparticles were introduced into mouse fibroblast (L929) for MTT test and Prussian blue staining analysis. Cellular uptake of the nanoparticles was assessed using magnetophoresis. In vitro scratch wound healing assay was carried out. It was observed that migrating cells had a long shape and were pointed in the direction of the magnetic force. The shape change is especially obvious when close to the magnets. Intracellular force on cells cued under different magnetic fields and accelerated cell migration by adjusting the magnetic fields and giving the cell free culture space, as shown in Fig. 1. The results showed that RGD/Dextran/Fe3O4 composite magnetic nanoparticles have good biocompatibility and are high potential candidate using cell tracking, cell therapies, and tissue engineering applications. In a wound healing model, a new level of control over cell migration could lead to significantly faster healing and less subsequent complications. This study provides an attractive prospect for the enhancement of directionally induced cellular migration through the use of an applied magnetic field.

Fig. 1 Manipulating directional cells migration with internalized magnetic nanoparticles in accordance with the applied external magnetic field.

B-351

PT-03

Synthesis and Characterization of Aqueous Magnetic Ferrofluid for Biomedical Application

Jefunnie Matahum, Chao-Ming Su, Shyh-Liang Lou, Tzong-Rong Ger

Department of Biomedical Engineering, Chung Yuan Christian University, Taoyuan, Taiwan

e-mail: sunbow@cycu.org.tw

Water based magnetic fluids are one of extensively researched nanomaterial for biomedical applications. The concept of double layer coating for ferrofluid provides double layer steric and electrostatic stablization of magnetic nanoparticles in water which gives more stability and prevents agglomeration. The goal of this study is to synthesize magnetic ferrofluids that can be applied for biomedical research. In the present work, Fe3O4 magnetic nanoparticles are synthesized by chemical coprecipitation. Aqueous ferrofluids are made by double layer stabilization of magnetic nanoparticles using lauric acid (LA) and dodecyl benzene sulfonic acid (DBS) as surfactant agents. The size of these nanoparticles obtained in Dynamic Light Scattering analyzer (DLS) is 59 nm. FTIR spectroscopy showed characteristic signals of hydroxide groups (-OH), and phenyl groups of DBS however peaks on Fe-O band and LA did not appear which is suggested to be masked by these signals as shown in Figure 1 (middle). In vitro cytotoxicity test of magnetic particles was evaluated using concentrations of 5-100 ug/mL. It was revealed that the ferrofluid exhibited cell survival rate of 70-99%. Preliminary experiments demonstrated the potential of the aqueous ferrofluid for biomedical research.

Figure 1. Ferrofluid under external magnet (left). Structure of Fe3O4 coated with Dodecylbenzene Sulfonic Acid and Lauric Acid (middle). Percentage distribution of ferrofluid (right).

B-352

PT-04

Magnetic Properties of Individual Magnetite

Nanoparticles

H. Mamiya(a), J. Nishigaki(b), M. Fukunaga(b), I. Furukawa(b), J. Cuya(b), and B. Jeyadevan(b)

(a) National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan (b) The University of Shiga Prefecture, National Institute of Materials Science

e-mail: MAMIYA.Hiroaki@nims.go.jp

In recent year, method for synthesizing magnetic nanoparticles has made remarkable progress. However, the true magnetic characteristics of the nanoparticles such as magnetic anisotropy is yet to be revealed due to interactions between nanoparticles. As a consequence, the application-oriented design of magnetic nanoparticles has become difficult. Thus in this study, we have prepared ideal interaction-free magnetite nanoparticle system by coating magnetite particles with silica of enough shell thicknesses and measured their magnetic properties to clarify the true magnetic anisotropy of individual magnetite nanoparticles.

First, magnetite particles with average diameters of 7.8 nm and 13.1 nm were synthesized. Then, these magnetite particles were coated with silica shell of thicknesses 20.8 and 28.9 nm, respectively. In the first-order reversal curve (FORC) diagrams, we can find that interaction field disappears with coating. In other words, the magnetite nanoparticles are magnetically isolated by the silica-shell. This fact can be confirmed by the proportional relationship between isothermal remanent magnetization and DC demagnetization remanence.

Using these well-isolated magnetite nanoparticles, the magnetic measurements yield intriguing information as follows: (A) Remanent magnetization from the magnetic saturation is just equal to a half of the saturation magnetization, and magnetization curves can be explained as the superimposition of Stoner-Wohlfarth hysteresis loops considering the switching field distribution derived from the remanence analysis. These results clearly indicates that uniaxial magnetic anisotropy is predominant in the individual magnetite nanoparticles in spite of the cubic symmetry of their crystal. (B) Blocking temperature distributions calculated from thermal decay curves of isothermal remanent magnetization at various applied fields show that the coercivity significantly varies even for the same size, although their mean value becomes higher when the size is smaller. These results indicate that the magnetic anisotropy is not only correlated with the surface/volume ratio, but also considerably affected by the other factors such as crystallinity, lattice strain, or particle shape. Further discussion will also be reported.

B-353

PT-05

Preparation of Magnetic Zeolite Materials and

Application in Biomedical Studies

V. Hovhannisyan, C. Y. Dong

Department of Physics, National Taiwan University, Taiwan e-mail: hovv@phys.ntu.edu.tw

Natural zeolites are widespread low-cost porous aluminosilicates that widely used

in agriculture, chemistry, industry, environmental protection, as well as in biomedicine for several decades [1]. Zeolite crystals consist of oxygen-sharing SiO4 and AlO4 tetrahedral groups united by common vertices in three-dimensional framework containing pores of 0.3 to 1.2 nm sizes. Due to exciting adsorption, cation-exchange, dehydration–rehydration, and catalytic shape selectivity, zeolites are used as effective light harvesting system in solar cells, as dietary supplements in animal diets and in the take-up of radioactive Cs and Sr from nuclear waste and fallout. Clinoptilolite type of natural zeolite (CZ) is safe for human. CZ is used in health industry as a food supplement against many diseases, including cancer, and as adsorbent of free radicals, toxic metals and radioactive elements. CZ is also suitable for delivery and controlled release of different drugs. Furthermore, it was demonstrated that some zeolites synthesized with magnetic nanoparticles revealed strong magnetic properties, which allowed to manipulate them, separate from other materials and use in MRI [2].

We prepared magnetic nano- and micro particles by incorporation of Fe3O4

nanoparticles into the CZ matrix to enhance biomedical applications of the natural zeolite. Moreover, our research showed that due to some content of magnetic compounds and fluorophores, natural CZ possessed enough magnetic momentum to respond magnetic field and optical radiation. The prepared CZ products had stable magnetic, optical and adsorption properties, and characterized by TEM, magnetometric and thermogravimetric instruments, confocal and multiphoton microscopy, UV-Vis spectrophotometry and spectrofluorimetry. The products were tested as new multimodal probes for optical imaging, controlled drug delivery container and thermotherapy sensor in cellular level and model organisms. Specifically, the interaction of photo-dynamically active dyes, as well as Au and Ag nanoparticles with CZ was investigated, and it was shown that individual ZL particles adsorbed hypericin, Zn-tetraporphyrin molecules, Ag nanoparticles, but did not adsorb fluorescein molecules. In addition, it was demonstrated that Hyp molecules were released from the CZ pores in the presence of biomolecules such as collagen, haemoglobin and lipids. Obtained results may open new perspectives in the research and application of magnetic zeolites in biomedicine. [1] F. A. Mumpton, Proc. Natl. Acad. Sci. USA, 96, 3463 (1999).

[2] E. Csajbok, I. Banyai, E. L. Vander, R.N. Muller, W.Z. Zhou, J.A. Peters,

Chem-Eur J. 16, 4799 (2005).

B-354

PT-06

Fig. 1. Magnetoresistance curves of the nanowires with widths of (a) 300 and (b) 500

nm before and after the attachment of magnetic beads. The magnetic field was swept

along the x axis.

Biomolecular detection and capture in wave sheet

ferromagnetic nanostructure

C. R. Jeng, H. T. Huang, and Z. Wei

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

e-mail: vfande245@hotmail.com Among various types of biosensors, magnetoresistance-based biosensors possess

several advantages including high sensitivity and being less interfered by the environment, and are therefore suitable for sensitive biodetection. Besides, the magnetic is not shielded by chemical compounds, microstructures, or another biomaterials, so the signals detected by the magnetoresistance-based biosensors are not influenced by the surrounding objects. In this report we present wave Permalloy nanowires with various line widths as a biomolecular sensing device. In this design, the magnetic poles on the apexes and valleys of the wave Permalloy nanowires can actively attract the magnetic beads immobilized biomolecular onto the nanowires for detection.

Permalloy nanowires deposited onto wave silicon grooves were designed as biosensing devices of nano magnetic beads, which modified by biomolecule. We applied a magnetic field along x axis, and measured the magnetoresistance curves of the nanowires before and after the attachment of magnetic beads by four-probe method. The stray field generated by the magnetized beads are against the magnetic moments of the wave sheet surfaced film, therefore making it harder for the switching process to occur. It was observed that the sensitivity 43.29% in switching field variation after magnetic beads were attached can be obtained when the field was applied perpendicular to the plane of the 300 nm wide nanowire, as shown in Fig. 1(a). The sensitivity 45.78% in magnetoresistance variation occurred in the 500 nm wide nanowire for the same field direction, as shown in Fig. 1(b).

B-355

PT-07

Magnetic nanoparticle enhanced surface plasmon

resonance for biosensing application

H. T. Huang, T. S. Lin, and Z. Wei

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

e-mail: vfande245@hotmail.com Magneto-optical Kerr effect has been widely used in the magnetic recording devices,

magnetic sensors, optical modulators and bio/medical sensors. However, the development is limited by the small microscopic magneto-optic signal, how to generate a larger magneto-optic Kerr signal has become a critical task for the academia. In this report we used surface plasma resonance (SPR) to enhance the magneto-optic Kerr signal on a continuous film (Glass/ t nm Co/45 nm Au, t = 3, 8, 18 and 28 nm). As we can see in Fig. 1(a), when the incidence angle of the laser reaches the SPR angle, the SPR is generated on the sample. The electrical fields in enhanced locally and further intensify the magneto-optic Kerr signal. The black curve in the Fig. 1(b) is the SPR curve and the blue curve is the enhanced Kerr signal curve, we can observe that the magneto-optic signal has a maximum enhance position near the SPR angle.

Fig. 1(a) Experimental setup (b) SPR (black) and the enhanced Kerr signal (blue)

curve.

B-356

PT-08

Magnetic properties of multilayered graphene oxide

reduced in hydrogen atmosphere

Y. Fujiwara, R. Mori, T. Tanaka, M. Jimbo , T. Kobayashi

Graduate School of Engineering, Mie University, Tsu 514-8507, Japan School of Engineering, Daodo University, Nagoya 514-8507, Japan

e-mail: fujiwara@phen.mie-u.ac.jp

Since a room temperature ferromagnetism of fullerene was reported (It has been retracted now.), many studies have been carried out theoretically and experimentally on the magnetism of nano-carbon materials [1-3]. Both theoretical and experimental studies have suggested that hydrogen adsorption on edges or surface of graphene sheets plays an important role in the ferromagnetism of graphene. In this work, a magnetism of multilayered graphene oxide sheets was investigated.

Multilayered graphene oxide sheets synthesized by modified Hummer's method were purchased. Preparation flow is as follows, 1. HCl treatment, 2. 1st reduction in Ar+H2 gas mixture, 3. sonication, 4. 2nd reduction in Ar+H2 gas mixture. For comparison, single-layer graphene oxide samples were also prepared. Magnetic properties were investigated by VSM at room temperature. XPS spectra were measured to observe the chemical changes. Magnetic impurities were confirmed by EPMA. TEM micrographs were also taken.

Figure １ shows typical C 1s XPS spectra of as-purchased and reduced multilayered graphene oxide sheets. After the reduction, it was recognized that functional groups containing oxygen almost disappeared. The multilayered samples showed the ferromagnetism and the Ms was approximately 0.01 emu/g. Magnetic impurities were estimated to be less than 10 ppm from EPMA measurements. On the contrary, obvious signals indicating the ferro-magnetism were not observed on the single-layer samples and the multilayered samples which prepared without sonication process. For the multilayered samples, TEM images revealed some damages and signs of exfoliation of a graphene layer. Thus, we have speculated that the observed ferromagnetic behavior is attributed to the graphene to which hydrogen is adsorbed asymmetrically with respect to the graphene plane [2]. [1] N. Ohta et al., J. Magn.Soc.Jpn. 34, 573 (2010). [2] J. Zhou et al., Nano Lett. 9, 3867 (2009). [3] Y. Wang et al., Nano Lett. 9, 220 (2009).

300 295 290 285 280 275

Inte

nsit

y [a

.u.]

Binding energy [eV]

as-purchased

H2 reduced

C-C

C-O

H or

C-O

-C

Fig.1 XPS spectra of graphene

oxide sheets before and after

hydrogen reduction.

B-357

PT-09

Investigation of magnetic properties of Co0.2Zn0.8Fe2O4 nanoparticles for hyperthermia applications

Sangjoon Lee, Sam Jin Kim, Chul Sung Kim

Department of Physics, Kookmin University, Seoul 136-702, Korea e-mail: cskim@kookmin.ac.kr

Co0.2Zn0.8Fe2O4 nanoparticles were prepared by high temperature thermal decomposition method [1]. The crystal structure, measured by x-ray diffraction, was cubic spinel with space group Fd-3m and the lattice constant (a0) of 8.4051 Å from Rietveld refinement analysis. Based on the Scherrer equation, the average diameter of nanoparticles was estimated to be 13.4 nm. The magnetic properties were investigated using a vibrating sample magnetometer and 57Fe Mössbauer spectroscopy. The values of saturation magnetization and coercivity of Co0.2Zn0.8Fe2O4 nanoparticles at room temperature were 86.75 emu/g and 31.66 Oe, respectively. The thermal properties for hyperthermia applications were measured by magneTherm device within physiologically safe ranges of frequency and amplitude. The self-heating temperature was estimated to be 123 and 129 oC at 50 and 112 kHz under 25 mT, respectively. [1] H. N. Choi, K. S. Baek, S. W. Hyun, I. B. Shim, and C. S. Kim, IEEE Trans. Magn., vol. 45, pp. 2554-2556 (2009)

B-358

PU-01

PLD-made Nd-Fe-B thick film magnets deposited on Si substrates and their micromachining

D. Shimizu(a), Y. Chikuba(a), A. Yamashita(a), M. Nakano (a), T. Yanai(a), R. Fujiwara(b), T. Shinshi(b), and H. Fukunaga(a)

(a)Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan

(b)Interdisciplinary Graduate School of Science and Engineering,

Tokyo Institute of Technology, Yokohama 226-8503, Japan e-mail: bb35212032@ms.nagasaki-u.ac.jp

Several researchers have reported Nd-Fe-B thick films on Si substrates with a metal

buffer layer prepared by a sputtering method [1][2], and the thickness of each film was

less than 100 μm. Recently, we demonstrated PLD (Pulsed Laser

Deposition)-fabricated Nd-Fe-B films with the thickness up to approximately 160 μm

on Si substrates without a buffer layer [3]. In the study, the effect of the boundary

between a Si substrate and a Nd-Fe-B film on various properties was investigated. This

contribution reports the mechanical together with magnetic properties of the samples

deposited on Si substrates with a thermal or a natural oxide film. Furthermore, a wet

etching process of a Nd-Fe-B film was carried out. Each rotated target with the

composition of NdXFe14B (x=2.0, 2.6, 3.0, 3.5) was ablated by an Nd-YAG laser. All

the as-deposited Nd-Fe-B thick films on SiO2 (a thermal or a natural oxide film)

/Si(100) substrates(5 mm × 5 mm : square) without a buffer layer had amorphous

structure, therefore they were crystallized by a pulse annealing (PA) method in the

vacuum atmosphere. Although the magnetic properties of films deposited on the both

oxide films were almost the same, a peeling phenomenon occurred in a Nd-Fe-B film

thicker than 20 µm from a Si substrate with a natural oxide film. The result was

different phenomenon of a Nd-Fe-B film deposited on a Si substrate with a thermal

oxide film [3]. Namely, in the previous experiment, even if a Nd-Fe-B film deposited

on a Si with a thermal oxide film was broken, the sample was destroyed from the inside

of the substrate. The result suggests that the thermal oxide film is indispensable to

obtain a strong adhesion between a Nd-Fe-B film and a Si substrate. In addition, we

confirmed no deterioration of magnetic properties after a chemical etching in a

Nd-Fe-B film prepared on a thermal SiO2/Si substrate.

[1] Y. Zhang et al., Acta Materialia, 60, 3783-3788 (2012).

[2] C. Zhi et al., International. J. Automation Technplogy, 7, 196-204(2013)

[3] M. Nakano et al., IEEE Trans. On Magn., 51, #2102604(2015).

B-359

PU-02

Magnetic Properties and Magnetocaloric effect in

La1-xNdxFe10.5Si2.5 (x = 0.2, 0.4, 0.6) Alloys

Wen-Zhe Nan(a), Tran Dang Thanh(a), Gnu Nam(b),

Tae-Soo You(b) , Seong-Cho Yu(a)

(a) Department of Physics, Chungbuk National University, Cheongju 361-763, South

Korea (b) Department of Chemistry, Chungbuk National University, Cheongju, 361-763,

South Korea

e-mail: scyu@cbnu.ac.kr In this report, we present a detailed studies on the magnetic properties and MCE of

La1-xNdxFe10.5Si2.5 (x= 0.2, 0.4, 0.6) alloys. The samples were prepared from pure

(99.9%) La, Nd, Fe and Si metals by an arc-melting method in a high purity argon

atmosphere. And then, the products were sealed in a fused-silica jacket under vacuum

and annealed at 1323 K for two weeks. According to the powder X-ray diffraction

patterns, the crystal structure of an as-cast sample displayed the elemental Fe-type

structure, but after the annealing process, they were transformed into the NaZn13-type

structure.

Magnetic measurements versus temperature (T = 70-300 K) and magnetic field (H

= 0-30 kOe) were performed on a vibrating sample magnetometer (VSM). The M(T)

curves for samples, all the samples exhibiting a ferromagnetic-paramagnetic (FM-PM)

phase transition at Curie temperature TC = 252, 250, and 246 K for x = 0.2, 0.4, and 0.6,

respectively. This FM-PM phase transition can be seen more clearly if H/M is plotted

versus M2 . The nonlinear parts in the low field region at temperatures below and above

TC are driven toward two opposite directions, revealing the FM-PM phase separation.

Based on isothermal magnetization data, M(H, T), we have calculated ΔSM(T) data for

samples under an applied magnetic field change H = 30 kOe. As a function of

temperature, the ΔSM(T) curves show a maximum (denote as |ΔSMmax|) at around their

TC. With H = 30 kOe, the values of |ΔSMmax| are found to be 3.8, 3.6, and 3.4 Jkg-1·K-1

for x = 0.2, 0.4, 0.6 samples, respectively. The nature of magnetic properties and MCE

in the La1-xNdxFe10.5Si2.5 alloys will be discussed thoroughly by mean of the effect of

Nd-doping concentration.

B-360

PU-03

Magnetic Iron implanted CuInSe2 thin film - A new room temperature diluted magnetic semiconductor

Chih-Hao Lee, Li-Jung Liu and Yu-Sheng Chen

Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan

e-mail: chlee@mx.nthu.edu.tw

The electronic structure and magnetic properties of an iron ion implanted CuInSe2

semiconductor thin film was studied. The X-ray diffraction and X-ray absorption

spectra show that the FeCu substitutions were formed at low doping range while Fe

clusters were formed at high level doping concentration. Room temperature

ferromagnetic property was observed from the results of the SQUID measurement,

which shows the sample has a ferromagnetic property. At low doping level, the

zero-field and non-zero field cool measurements show two curves almost identical.

While at high doping level, these two curves only merged at the temperature slightly

higher than the room temperature, which implies that at high doping level, the

ferromagnetic property is originated from a cluster with the blocking temperature

slightly higher than the room temperature. This result implies that at high doping level,

the ferromagnetic property is originated from Fe clusters with the blocking temperature

higher than the room temperature. For the low doped samples, the zero field cool and

non-zero field cool experiments did not show any evidence of an existence of blocking

temperature even down to 5 K, which implies no Fe clusters are formed. Formation of

the FeCu atoms are most likely.

B-361

PU-04

Magnetic properties and thermal stability of amorphous CoFeSiBHf thin films

M. Jimbo(a) , Y. Fujiwara(b) , T. Shimizu(a)

(a)School of Engineering, Daido University, Nagoya 457-8530, Japan (b)Graduate School of Engineering, Mie University, Tsu 514-8507, Japan

e-mail:jimbo@daido-it.ac.jp

Amorphous(a-) CoFeSiB alloy has exhibited excellent soft magnetic properties, and there have been many articles on the magnetic properties and the structures of a-CoFeSiB ribbons [1]. The a-CoFeSiB thin film is a promising material for a thin film yoke and a multilayered magnetic core. In our previous paper [2], we have reported a thermal stability of a-CoFeSiB thin films and an influence of Hf addition on the thermal stability. In this study, we report the magnetic properties and thermal stability of a-CoFeSiBHf thin films in detail.

The a-CoFeSiBHf thin films were prepared by RF magnetron sputtering onto water-cooled glass substrates. The CoFeSiB alloy target was utilized for the sputtering and a content of Hf was controlled by a number of Hf chips on the target. A static magnetic field of 100 Oe was applied parallel to the substrates during the deposition.

Figure 1 shows 4πMs and Hc of a-CoFeSiBHf films before and after an annealing at 400 ºC for 1 hour as a function of Hf content. Hc was estimated from easy-axis loops. For as-deposited films, 4πMs decreased with increasing Hf content monotonically, whereas Hc was almost independent on Hf content. After the annealing, 4πMs of a-CoFeSiB film decreased approximately 15 %, and Hc became 650 times larger to 130 Oe reflecting the ccrystaliztion of the film. On the contrary, for the a-CoFeSiBHf films, although 4πMs slightly decreased by the annealing, an increase in Hc was not significant. Especially, when Hf content was larger than 5 at.%, Hc only slightly increased from 0.15 Oe to 0.4 Oe by the annealing. Since XRD peaks indicating the crystalization in the annealed films were not observed, it is recognized that the addition of Hf is effective technique to raise the cystallization temperature of a-CoFeSiB thin films. [1] H. Fujimori et al., Sci. Rep. Res. Inst., Tohoku Univ., Ser. A 26, 36 (1976). [2] M. Jimbo et al., J. Appl. Phys., 117, 17A313 (2015).

Fig.1 Hf content dependence of

magnetization and coercivity of

a-CoFeSiBHf films.

B-362

PU-05

Optimization of target composition in Nd-Fe-B film magnets prepared by high laser energy density

H. Kondo, A. Yamashita, M. Nakano, T. Yanai, and H. Fukunaga

Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan e-mail: bb35212030@ms.nagasaki-u.ac.jp

Miniaturized electronic devices comprising anisotropic Nd-Fe-B film magnets have

been reported by a lot of researchers [1][2]. Recently, our group reported isotropic

Nd-Fe-B+α-Fe dispersed nano-composite film magnets prepared by a PLD method

with laser energy density (LED) > 10 J/cm2 in order to apply the films to a

multi-polarly magnetized rotor for a miniaturized cylindrical motor [3]. Although the

targets had Nd-rich compositions compared to a stoichiometric one such as Nd2.4Fe14B

or Nd2.6Fe14B, the above-mentioned nano-composite structure together with good

magnetic properties of Br > 0.9 T, Hc > 300 kA/m, and (BH)max > 90 kJ/m3,

respectively, could be obtained. This contribution reports the influence of structure,

surface morphology and magnetic properties on target compositions for the isotropic

Nd-Fe-B film magnets prepared at LED > 10 J/cm2. An Nd-Fe-B film was deposited on

a Ta substrate by ablating each rotated target with eight compositions of NdXFe14B (X

= 1.8, 2.0. 2.2, 2.4, 2.6. 2.8, 3.2, 3.5) in the vacuum atmosphere of 10-5 Pa. An Nd-YAG

pulse laser with LED above 10 J/cm2 was could be obtained by a laser beam with the

diameter less than 1 mm. All the as-deposited films thicker than 10 μm were

crystallized by a pulse annealing (PA) method in the vacuum atmosphere. The

observation of X-ray diffraction patterns indicated that the all as-deposited films had

amorphous structure with α-Fe grains. The result suggests that a usage of the small

laser beam of high LED enabled us to precipitate α-Fe phase even if we used an

Nd-Fe-B target with large amount of a Nd element such as Nd3.2Fe14B and Nd3.5Fe14B.

Moreover, the number and/or size of droplets with Nd-rich composition drastically

increased as X of an NdXFe14B target became larger than 2.6 and the residual magnetic

polarization decreased. On the other hand, the coercivity of films prepared by

NdXFe14B (X=1.8, 2.0, 2.2) targets showed less than 300 kA/m. Resultantly, the X

range from 2.4 to 2.6 in a NdXFe14B target is optimum in order to achieve good

magnetic properties in Nd-Fe-B films prepared by using a PLD with LED > 10 J/cm2.

[1] Y. Zhang et al., Acta Materialia, 60, 3783-3788 (2012).

[2] C. Zhi et al., International. J. Automation Technplogy, 7, 196-204(2013)

[3] M. Nakano et al., IEEE Trans. On Magn., 51, #2102604(2015).

B-363

PU-06

Development of anisotropic R-Fe-B powders with high

performance

Jinbo Yang， Jingzhi Han， Yingchang Yang School of Physics, Peking University, P.R. China

Nd2Fe14B-type permanent magnets are widely used because of their excellent

magnetic performance at room temperature. Anisotropic Nd2Fe14B material may have

much higher maximum energy product (BH)max than that of the isotropic materials,

which is appropriate for the preparation of anisotropic Nd-Fe-B bonded or sintered

magnets with high performance. The hydrogenation-disproportionation-desorption-

recombination (HDDR) process is an effective method to prepare anisotropic

Nd2Fe14B-type magnetic powders. However, the origin of the crystal texture

(anisotropy) in the HDDR powders is in dispute till now. Moreover, relative low

coercivity limits their applications at high temperature. We have used R-Cu( R=Nd,Pr,)

alloy diffusion effect to further improve the magnetic properties of HDDR

R-Fe-B( R=Nd,Pr). The diffusion of R-Cu alloys into the powders can prevent the

grain from growing, and improve the coercivity of the powders. However, the

coercivity enhancement is on the basis of obviously sacrificing the remanence, and the

diffusion treatment also increases costs of the product. In this work, HDDR

phenomenon was experimentally observed to take place in a single crystal Nd2Fe14B

grain. We found that a rod-like disproportionated microstructure with self-organized

hexagonal RH2 nanorods embedded in Fe matrix is very important for the formation of

the crystal texture. The grain sizes of HDDR Nd2Fe14B-type magnetic powders can be

refined from 400 to 250 nm by modifying alloy composition and optimizing HDDR

process. Nd2Fe14B-type magnetic materials with a coercivity of 18 kOe and the

maximum energy products (BH)max higher than 40 MGOe were achieved. The

domain structures observed using Lorentz TEM suggests that modified boundaries can

work as effective pinning layers for domain walls. This indicates that HDDR process

can be optimized to enhance the texture and coercivity of Nd-Fe-B without the alloy

diffusion.

B-364

PU-07

A study of the origin of large positive magnetostriction in Fe-B single-crystal films

Tetsuroh Kawai(a), Mitsuru Ohtake(a) (b), and Masaaki Futamoto(a)

(a)Faculty of Science and Engineering, Chuo University, Bunkyo-Ku, Tokyo 112-8551, Japan

(b) Faculty of Engineering, Kogakuin University, Hachioji, Tokyo 192-0015, Japan e-mail: kawai@futamoto.elect.chuo-u.ac.jp

The large positive magnetostriction of Fe-B based amorphous alloys causes audible noise when they are employed as core materials in transformers. Therefore, it is important to investigate the origin of large magnetostriction. In the present study, variations of magnetostriction constants(100, 111) in Fe-B alloys are compared with those measured for Fe-Al alloys[1], and the origin of large magnetostriction in Fe-based soft magnetic material is discussed.

Fe-B and Fe-Al alloy films were prepared on MgO(001) single-crystal substrates using an UHV RF magnetron sputtering system. Magnetostriction was measured by a cantilever method under rotating magnetic fields. Magnetic properties were evaluated by VSM and broadband FMR[2].

Dependences of magnetostriction constants on alloy composition are compared for Fe-B and Fe-Al single-crystal films in Fig. 1. The variations on alloy composition are very similar, which suggests that the physical origin of magnetostriction is similar between the Fe-B and the Fe-Al alloys where both alloy elements(B, Al) belong to Ⅲb in the periodic table. The relationships between large magnetostriction and g-factors estimated by FMR measurements are discussed.

Fig. 1 Alloy content dependences of magnetostriction constants,100 and 111, for (a) Fe-B and (b) Fe-Al single-crystal films.

[1] T. Kawai et al., to be published in AIP Advances 6 (2016). [2] S. Takeda et al., J. Magn. Soc. Jpn., 39, 227 (2015).

B-365

PU-08

Microwave Hydrothermal Synthesis and Magnetic properties of Nanocrystalline Y3-xGdxFe5O12 garnets for

microwave circulator applications T.Ramesh (a), R.S.Shinde (b), S.R.Murthy (c)

(a)Department of Physics, BVRIT Hyderabad College of Engineering for Women,

Hyderabad, India. (b)Ferrite Laboratory, RRCAT, Indore, India.

(c)Department of Physics, Geethanjali College of Engineering and Technology, Hyderabad, India.

e-mail: rameshouphysics@gmail.com

Nanocrystalline Y3-xGdxFe5O12 garnets were synthesized using microwave

hydrothermal (M-H) method by controlling process parameters such as temperature,

pressure and pH. Phase structure of all the powders was confirmed by using x-ray

diffraction (XRD) from which the crystallite sizes are found to be in the range of 13-25

nm. The particle size measured with FESEM and it is in the range of 12-22 nm. The

weight loss in synthesized powders during thermal treatment was measured using

thermo gravity and differential thermal analysis (TG/DTA) is found to be 10-15%

within the temperature range of 50⁰C-1000⁰C. DSC measurements were carried out to

find the phase transition and it is observed around 560 K. The nanosize powders were

microwave processed at 1100⁰C/60 min. The processed samples were characterized by

using XRD and FESEM and the obtained grain sizes are in the range of 80-110 nm.

Complex permittivity and permeability properties were measured in the frequency

range of 1kHz-1.8GHz. Magnetic properties such as MS and HC were measured at

different temperatures. Results of magnetic properties show that the saturation

magnetization is decreased in a linear manner and temperature stability increases with

increasing the Gd3+ concentration (x). Curie temperature is slightly shifting towards

high temperature by increasing the Gd3+ concentration. The observed dielectric

constant is in the range of 13 -16, the dielectric and magnetic losses are in the order of

10-3 and 10-2 respectively. The low dielectric, magnetic losses, moderate saturation

magnetization and high-temperature stability properties exhibited by Gd3+ substituted

YIG ferrites makes them find applications in microwave devices such as circulators

and isolators etc.

B-366

PU-09

The effect of Nd-Cu addition on the coercivity of hot-deformed magnet prepared with HDDR powder

Haihang Wang(a), Renjie Chen(a), Wenzong Yin(a), Chaoxiang Jin(a), Zexuan Wang(a), Doo Lee(b), Aru Yan(a)

(a)Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and

Engineering, Chinese Academy of Sciences (b)University of Dayton

HDDR (hydrogenation disproportionation desorption recombination) has attracted much attention for refining grain size and recycling waste magnets. [1-2] However, the coercivity of deformed magnets prepared by HDDR-processed powders (HDDR magnet) are far below the expected value based on their submicron grains, which is attributed to the lack of continuous ultrathin Nd-rich intergranular phase between neighboring Nd2Fe14B matrix grains. [3]

In this work, the grain boundary diffusion process has been employed to the hot-press and die-upset process in order to improve the microstructure of the HDDR magnets. The HDDR-processed Nd-Fe-B powders with the nominal composition of Nd28Pr0.3Ga0.33Nb0.23Febal.B1.05 (wt. %) were used as the starting materials. The low melting-point Nd70Cu30 (wt. %) eutectic ribbons were crushed into powders with 100 - 150 μm, and then were mixed with the HDDR-processed powders at a mass fraction of x (x=0 - 4 wt. %). Hot pressed magnets were fabricated in vacuum with the mixed powders, and the hot pressed precursors were deformed with the height reduction of 70%. The hot deformed magnets were annealed at 550-1000 in vacuum.

Figure 1(a) shows the tendency of the coercivity and remanence vs the Nd-Cu addition mass. The coercivity of the hot-deformed magnets with 2 wt. % Nd-Cu additions increased by 241 % from 3.81 to 10.4 kOe, in comparison with that of the initial HDDR magnets without Nd-Cu. And the coercivity was improved without sacrificing the remanence seriously, which decreased from 12.5 to 12.1 kGs. However, we also found the partial aggregations of the non-diffused Nd-Cu phase in the hot-pressed magnets, as shown in Fig 2. Considering the short hot-deformation procedure, the Nd-Cu alloy couldn’t be distributed in the hot-deformed magnets uniformly. To overcome this problem, the hot-deformed magnet with 2 wt. % Nd-Cu addition underwent the annealing treatment. As Fig 1(b) presented, the coercivity increased from 10.4 to 13 kOe monotonously until the annealing temperature up to 900 oC, which might result from the sufficiently diffused of Nd-Cu alloy around matrix grains. However, the remanence started decreasing when the temperature exceeded 650 oC. Thereafter, the mechanism of enhanced coercivity based on the detailed microstructure characterization is investigated and discussed systematically. [1] T. Takeshita, R. Nakayama, Proceedings of the 11th Workshop on Rare Earth Magnets and their Applications, Pittsburg, USA, 1990, pp. 49–71. [2] Périgo E A, da Silva S C, Martin R V, et al . Journal of Applied Physics, 2012, 111(7): 07A725. [3] H. Sepehri-Amin, T. Ohkubo, T. Nishiuchi, S. Hirosawa, and K. Hono, Scripta Mater, vol. 63, no. 11, pp. 1124–1127, 2010

Fig. 1 (a) remanence (Br) and coercivity(Hcj) of hot deformed magnets as a function of different Nd-Cu alloy addition. (b) Remanence (Br) and coercivity (Hcj) of hot-deformed magnets with 2 wt. % Nd-Cu additions as a function of different heat treatment temperature.

Fig.2 (a) BSE SEM image showing the interface of hot pressed magnet, (b)(c)(d) EDS maps of elements in this area

(a) (b)

B-367

PU-010

Combined effect of stress and magnetic field on domain in new Fe-based

amorphous alloys

Chengliang Zhaoa, Aina Heb, Anding Wangc, Chuntao Changd, Xinmin Wange Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Key

Laboratory of Magnetic Materials and Devices, and Ningbo Institute of Materials Technology &Engineering, Chinese Academy of Sciences, Ningbo 315201 China

azhaocl@nimte.ac.cn, bhean@nimte.ac.cn, canding@nimte.ac.cn, dctchang@nimte.ac.cn, ejbmgwang@yahoo.co.jp

Keywords: Fe-based amorphous alloys, Domain structure, Stress annealing, Magnetic field annealing.

Fe-based amorphous soft magnetic alloys have aroused wide interests both in scientific and technological worlds, for their combining of good magnetic properties including high saturation magnetic flux density (Bs), low coercivity (Hc), low core loss and high permeability (μe). However, Fe-based amorphous soft magnetic alloys are more stress sensitive than traditional Si-steels. Stress of different directions and intensity can be involved because of winding and self-gravity. It is still not clearly known how stress affects the magnetic properties. Further investigations are essential to explore the mechanism.

In our previous work, via component design and composition optimization, new Fe-based amorphous alloys with high Bs of 1.67 T and high GFA were successfully developed[1]. Excellent soft-magnetic properties and good manufacturability make it a promising candidate for application in electric devices. The good ductility after annealing makes this Fe-based alloy an ideal material to analyze the effect of stress and magnetic field on magnetic properties. In this study, domain structures were systematically examined after heat treatments under multiple stress and different field. Fig. 1 shows the domains in zero-stress, tensile stress in longitudinal and transversal direction. It was found that different tensile stress plays contract role in affecting soft-magnetic properties. Domain structure after different treatment was useful to explain the magnetic behavior. The independent and combined impacts were studied and the mechanism will also be discussed. [1] A.D. Wang, C.L. Zhao, H. Men, A.N. He, C.T. Chang, X.M. Wang, and R.W. Li, J. Alloy Compd. 630, 209 (2015).

Fig.1 Domains of FeSiBPC amorphous alloy under (a) zero stress, (b) longitudinal stress and (c) transversal stress.

B-368

PU-011

Mössbauer studies of Ba3Zn2Fe24O41 Z-type hexaferrite

Jung Tae Lim(a), Jung Chul Sur(b), In-Bo Shim(a), Chul Sung Kim(a)*

(a) Department of Physics, Kookmin University, Seoul, 02707, South Korea (b) Department of Microelectronics and Display Tech., Wonkwang Univ., Iksan,

54538, South Krea e-mail: cskim@kookmin. ac.kr

The Ba3Zn2Fe24O41 polycrystalline sample of Zn doped Z-type hexaferrite was

prepared by using solid-state-reaction methods. The high purity BaCO3, ZnO, and

Fe2O3 powders mixed in the appropriate stoichiometric ratio for Z-type hexaferrite and

was sintered at 1250 oC in air. The crystalline structure of sample was investigated by

x-ray diffractometer (XRD), and the magnetic properties of sample were measured by

vibrating sample magnetometer (VSM), and Mössbauer spectrometer. From the XRD

pattern of analyzed by Rietveld refinement method at room temperature, the samples

were found to be single-phased that the Bragg factor (RB) and structure factor (RF) were

less than that 5 %, and the crystal structure of sample was determined to be hexagonal

with space group p63/mmc. The lattice constants of sample were a0 = 5.90 and c0 =

52.64 Å. From the magnetic hysteresis curves at 295 K, the saturation magnetization

(Ms) and coercivity (Hc) of samples were Ms = 58.70 emu/g and Hc = 69.58 Oe,

respectively and samples show the ferrimagnetic behavior. Based on the temperature

dependence of the zero-field-cooled (ZFC) magnetization curves under 100 Oe

between 4.2 and 800 K, the sample showed the spin transitions from planar order to

uniaxial order around 400 K, and Curie temperature (TC) showed at 613 K. Mössbauer

spectra of sample were taken and analysed at various temperatures ranging from 4.2 to

700 K. From the relative areas fitted of the Mössbauer spectra, Zn ions preferentially

occupy the tetrahedral sublattices.

B-369

PU-012

Spin reorientation of Li0.99Na0.01FePO4 with Mössbauer Spectroscopy

Byung Ug Ko(a), Young Bae Lee(b), Bo Ra Myoung(a) and Chul Sung Kim(a)*

(a)Department of Physics, Kookmin University, Seoul, 02707, South Korea

(b)Department of Liberal Arts, Hanzhong University, Donghae, 25800, South Korea

*e-mail: cskim@kookmin.ac.kr

The secondary battery cathode material lithium iron phosphate (LiFePO4) has been

studied about performance improvement. Representatively, Li ion or Fe ion of

LiFePO4 were substituted others ion [1]. The starting materials of this sample were

FeC2O4·2H2O, NH4H2PO4, Na(CH3COO) and Li2CO3 and synthesized by solid state

method. The mixture was calcined at 300 C for 4 hours under argon atmosphere and

sintered at 700 C for 10 hours under argon atmosphere. The synthesized

Li0.99Na0.01FePO4 sample was measured by XRD (x-ray diffractometer) and analysed

by Fullprof program. This sample was determined to be orthorhombic with the space

group Pnma. The lattice constants were determined a0 = 10.327 Å, b0 = 6.007 Å and c0

= 4.693 Å. The Bragg factor RB and structure factor RF were about 5%. In order to

measured magnetic properties, we measured VSM (vibrating sample magnetometer)

and Mössbauer spectra at various temperature from 4.2 to 300 K. The results indicated

that Néel temperature (TN) and spin reorientation temperature (TS) were TN = 50.5 K

and TS = 22 K. From analysed Mössbauer spectrum, at 4.2 K, the magnetic hyperfine

field (Hhf), electric quadrupole splitting (ΔEQ) and isomer shift (δ) values was

determined to be Hhf = 124.53 kOe, ΔEQ = 2.74 mm/s, δ = 1.24 mm/s. θ = 0.0 , φ = 0.0 ,

η = 0.82 and R = 3.25 and ΔEQ = 2.95 mm/s and δ = 1.11 mm/s at 295 K. The Fe ion

state of Li0.99Na0.01FePO4 powder sample was Fe2+. [1] J. Wang and X. Sun, Energy Environ. Sci., 8, 1110 (2015)

B-370

PU-013

High Energy Product and Coercivity enhancement of

sintered Nd-Fe-B magnets by grain boundary diffusion

Yang Zhao(a,b), Haibo Feng(a), Anhua Li(a), Minggang Zhu(a), Wei Li(a)

(a)Division of Functional Materials, Central Iron and Steel Research Institute,

Beijing 100081, P.R.China (b)School of Materials Science and Engineering ,Tsinghua University,

Beijing 100084, P.R.China e-mail:sa4141net@163.com

Grain boundary diffusion with Dy compound nanoparticles was applied to the

sintered Nd-Fe-B magnets，investigating the changes in magnetic and microstructural

properties of the magnets and clarified the optimum diffusion temperature and time.

Through controlling the diffusion temperature and time, the coercivity was increased

from 12.57 to 18.54 kOe and the high energy product increased from 50.1 to 50.5

MGsOe. After further improved the diffusion temperature，the coercivity reached to

22.69kOe with an obvious high energy product decrease. Investigation shows that Dy

diffuses from the grain boundary phases into the Nd2Fe14B grains, substituting for Nd

to form the (Nd, Dy)2Fe14B core-shell phases in the outer region of the grains. The

substituted Nd improves the grain boundary structure which contributes to the high

energy product and coercivity enhancement. As the diffusion temperature improved,

Dy further diffuses to the Nd2Fe14B grain core which decreases the high energy

product.

B-371

PU-014

High performance R-Fe-B die-upset magnets based on misch-metal alloys

R. Lai (a), R. Chen (a), W. Yin (a), X. Tang (a), Z. Wang; (a), D. Lee (b), A. Yan (a) (a) Rare Earth Magnetic Materials Laboratory, Ningbo Institute of Materials

Technology & Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, China. (b)University of Dayton, Dayton, OH, United States.

Nd-Fe-B permanent magnets have been widely used in many fields because of their outstanding magnetic

properties[1]. However, Pr,Nd and Dy are now considered to be critical elements due to an increasing demand. Therefore,

researchs on substitution of Pr-Nd by Ce or misch-metal alloys (MM) are attracting renewed attention because of their

potential applications in permanent magnets[2][3]. The intrinsic magnetic properties of La2Fe14B and Ce2Fe14B are far

inferior to those of Nd2Fe14B, so it is hard to acheive high performance R-Fe-B magnets based on misch-metal which

contains a majority of La and Ce elements through conventional methods.

In this work, misch-metal alloys based nano-structured die-upset magnets were fabricated by dual alloy method. The

ribbons were rapidly quenched by ingots with nominal compositions of MM29.65Fe69.45B0.9 (MM: La ~ 23.17 wt.%, Ce ~

53.96 wt.%, Pr ~ 5.16 wt.%, Nd ~ 17.7 wt.%). Then these melt-spun powers were mixed with commercial available

MQU-F powers, the MM-Fe-B melt-spun powers mass fraction is 0 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.%. The

die-upset magnets were made by the blended powders. As the ratio of MM rise, the coercivity (Hcj) of the R-Fe-B magnets

decreases almost linearly, while no significant decline of the remanence (Br) was obsevered (Fig. 1). It is quiet promising

that a high-performance R-Fe-B magnet with a remanence Br of 13.46 kGs, a coercivity Hcj of 10.69 kOe and a energy

product (BH)max of 43.5 MGOe was prepared when the MM-Fe-B mass fraction is 30 wt.%. Furthermore, the magnetic

properties can be enhanced by the following low-temperature heat treatment. The processed magnets can maintain good

textures, and the high remanences (Br) were resulted from alignment of the c-axis along the die-upsetting direction.

Backscatter electron (BSE) SEM images and Energy Dispersive Spectrometer (EDS) maps (Fig. 2) suggest that La2Fe14B

phase is hard to form, La elements tending to diffuse into the Nd-rich grain boundary phase during the substitute process,

while Ce elements tend to diffuse into Nd2Fe14B matrix phase uniformly. This pathway obviously benefits to produce

high-performance R-Fe-B-based magnets.

[1]J.J.Croat et al., J.Appl.Phys.55(1984) 2078–2082.

[2] J. F. Herbst et al., J. Appl. Phys. 111, 07A718 (2012).

[3] Niu E et al., J. Appl. Phys. 115(11),113912(2014).

Fig.1 Demagnetisation curves of the R-Fe-B die-upset magnets depending on MM-Fe-B mass fraction.

Fig.2 BSE images and corresponding Nd, La, Ce, and Fe elements distribution of R-Fe-B die-upset magnet with 50wt.% MM-Fe-B addition.

B-372

PU-015

High rated current Fe-base metal core multilayer power inductor

C. P. Wu, W. S. Ko, Y. T. Haung, Y. P. Wang, L. J. Wang and M. J. Tung

Material and Chemical Research Laboratories Industrial Technology Research Institute, Taiwan

e-mail: itria20161@itri.org.tw Recently, mobile devices are growing popularity in human life, and make very

valuable and developing markets. Newer developments in mobile devices technology

tend to be embedded, networked, multifunctional and individual. Take the smart phone

as an example, the trends take of using high-speed multicore processors to satisfy

multi-application functions and high efficiency simultaneously. Such processors

require very high current for suppling power to each core. In addition, to meet the

smaller and thinner design of smart phone, there is increasing demands for smaller and

lower-profile electronic components. At a result, higher operating current power

inductor in a small size is needed. In order to achieve this demand, the optimizing

design of characteristics for core material, coil pattern and layer structure are very

important and necessary.

In our study, the magnetic circuit simulation of multilayer power inductor with

higher saturation magnetic flux iron base material is carried out by 3D finite element

analysis, because it is not suitable to apply the conventional method to calculate the

inductance of MLFC inductor. [1] With optimizing simulation designs the power

inductor has been made by conventional multilayer process. The experimental results

show that power inductor characteristics has inductance 50 to 596nH with less than

0.09Ω DCR value and the rate d current is 3.5 to 9A in

the total volume of 3.0mm x 2.4mm x 0.8mm. However,

experimental data and simulation results for different

turns of coil N and magnetic permeability μ are shown in

figure 1, and experimental data have a good agreement

with simulation results of u=10. With these result, our

reported method of magnetic circuit simulation can

provide a very useful reference to optimizing the

characteristics of iron base material core multilayer

power inductor for satisfying simultaneously higher

operating currents and smaller package demands. [1] Yu-Ting Huang, IEEE Transaction on Magnetics, 31, 6 (1995).

Fig. 1 Coil N dependence of

inductance with different

magnetic permeability μ.

B-373

PU-016

Effects of oxygen contents on the microstructures of high-performance SmCo 2:17-type sintered permanent

magnet Wei Sun(a)(b), Minggang Zhu(a)(b), Yikun Fang(a)(b), Hongsheng Chen(a)(b), Kuikui

Song(a)(b), Nengjun Yu(a)(b) ,Wei Li(a)(b) (a)Functional Materials Research Institute, Central Iron & Steel Research Institute, Beijing 100081, China.

(b) Beijing Engineering Laboratory of Advanced Metallic Magnetic Materials and Preparation Techniques, Beijing

100081, China.

Precipitation-hardened Sm2Co17 based sintered permanent magnet has been attracting a great deal of attention due to its distinguished high temperature magnetic properties, extremely low temperature coefficient, excellent corrosion resistance and oxidation resistance [1-3]. In this study, magnetic properties and microstructures of Sm2Co17-based sintered permanent magnets with the nominal composition Sm(CobalFe0.245Cu0.07Zr0.02)7.8 have been investigated. The magnets were prepared using the conventional powder metallurgy method, in which the pulverizing of powder is jet-milling and ball-milling, respectively. The typical demagnetization curves of the sintered magnets obtained by jet-milled and ball-milled powders are shown in Fig. 1. The corresponding magnetic properties of the magnets made of ball-milled powders (the magnet is designated as Mb) are: the remanent magnetic polarization intensity Jr=1.157 T (11.57 kGs), the intrinsic coercivity Hcj=752 kA/m (9.46 kOe), and the maximum magnetic energy product (BH)max=221 kJ/m3 (27.8 MGOe), while that of jet-milled powder (the magnet is designated as Mj) are: Jr=1.146 T (11.46 kGs), Hcj=2497 kA/m (31.37 kOe), and (BH)max=251.7 kJ/m3 (31.64 MGOe). The cause of such a significant difference between the two kinds of samples is expected as the existed deviation in effective chemical compositions, due to the different oxygen contents introduced during fabrication for the two kinds of magnets: ~2800 and ~1300 ppm.

Fig. 1. Demagnetizing curve of the magnet made of jet-milled powders measured by Pulsed Field Magnetometry. Insert is

the hysteresis loop of the sample.

References:

[1] Kronmüller H, Goll D. Analysis of the temperature dependence of the coercive field of Sm2Co17 based magnets.

Scripta Mater. 2003, 48(7):833.

[2] Wei Sun, Minggang Zhu, Yikun Fang, Zhiying Liu, Hongsheng Chen, Zhaohui Guo and Wei Li. Magnetic properties

and microstructures of high-performance Sm2Co17 based alloy. J Magn Magn Mater. 2015, 378:214.

[3] Minggang Zhu, Wei Sun, Haibo Feng, Yanfeng Li, Yikun Fang, Dong Zhou, Wei Li. Effects of Sm content on thermal

stability of Sm2Co17 sintered magnets. Journal of the Korean Physical Society. 2013, 63(3):784.

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B-374

PU-017

Effect of phase structure on remanence thermal stability of Alnico8 alloys

J.T.Zhao,Y.L.Sun, Z.Liu, D.Lee,L.Liu, X.C.Fengand A.R.Yan

Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo

Institute of Material Technology and Engineering, ChineseAcademy of Sciences,Ningbo, China

With the development of technology and application requirements, researchers pay attention to

not only magnetic properties of Alnico alloy but also its thermal stability. Their magnetic properties keeps in closely touch with phase microstructure[1], also Liu focuses on the effect of orientation degree of precipitated phase on thermal stability[2]. This paper mainly studies the influence of phase structure to thermal stability of Alnico8 alloys by adjusting the contents of Co and Nb(Sample A:36wt%Co; Sample B:36wt%Co, 1.1wt%Nb; Sample C:35wt%Co, 1.1wt%Nb). The morphology is characterized by Transmission Electron Microscope, the magnetic properties are measured by the B-H apparatus with closed circuit.

The room-temperature magnetic properties of remanence, coercivity and magnetic energy product of Sample C is 10.92KGs, 1695Oe and 12.48MGOe respectively. Fig. 1 shows Nb will decrease fluctuation of the temperature coefficient of remanence(short for a), meanwhile decreasing the content of Co is favorable to decrease the a. The a(RT-180) of Sample C is -1.26%%/. The white arrows indicate Nb can improve the uniformity of distribution and morphology of the precipitated phase and stop the small precipitated phase in the matrix phase(as showed in Fig. 2(a)、2(b)、2(c)). The white circle manifest the bifurcation phenomenon of the precipitated phase diminish gradually reducing further the content of Co, which will enhance the length and orientation degree of the precipitated phase(as showed in Fig. 2(d)、2(e)、2(f)). XRD analysis shows from Sample A to Sample C the orientation degree of precipitated phase indicated by I100/I200 gradually increase. Sample C shares the highest the sum content of Fe、Co and nFe/nCo in the precipitated phase, which means phase composition distribution is more homogeneous. The outstanding orientation degree and well-distribution of the precipitated phase promote Alnico8 alloys to get excellent thermal stability. Meanwhile the higher the sum of Fe、Co and nFe/nCo in the precipitated phase may have the similar effect as well.

[1] Lin Zhou, M.K. Miller, et al., Architecture and magnetism of alnico, Acta Mater, 74(2014) 224-233.

[2] Tao Liu, Wei Li, et al., Effect of Co on the thermal stability and magnetic properties of Alnico 8 alloys, J. Appl. Phys.

115, 17A751(2014).

Fig. 1 The curve of the remanence temperature coefficient against temperature of Alnico8 alloys

Fig. 2. TEM images of Alnico8 alloys: (a) Sample A, transverse; (b) Sample B, transverse; (c) Sample C, transverse; (d)Sample A, longitudinal; (d)Sample B, longitudinal; (d)Sample C, longitudinal.

B-375

5th August, Friday

B-376

HA-01

Investigation of the Origin of Ferromagnetic Signal

Observed in Locally Functionalized Graphene Layers

Wondong Kim

Center for Nano-metrology, Division of Industrial Metrology

Korea Research Institute of Standards and Science

The possibility to induce a magnetic property in graphene by various methods has been generating

much interest, because this would allow novel spintronic devices where charge and spin manipulation could be

combined. Theoretically, the formation of ferromagnetic order in graphene containing point defects or

functionalized graphene has been predicted repeatedly in the recent works. The observations of ferromagnetic

signals at room temperature have been reported for graphene or graphite which have points-defects produced

by various methods, but there are still controversies concerning (1) the role of possible contamination and (2)

the mechanism responsible for the strong interaction required for the formation of ferromagnetic ordering. In

the very recent report, it has been claimed that point-defects in the graphene only produce spin-half

paramagnetism, and the ferromagnetic order observed in the previous studies resulted from the existence of

small amounts of magnetic impurities. In case of functionalized graphene, it has been predicted that the

ferromagnetic ordering exists at the oxidized graphene layer where C atoms have C-OH, C-O-C or C=O bonds,

and for the semi-hydrogenated graphene sheet. Experimentally the existence of ferromagnetic order below 100

K in the n-doped graphene oxide layer has been confirmed with SQUID measurement, but the possibility of

magnetic contamination was not examined strictly.

Recently, we observed the ferromagnetic signal in Magnetic Force Microscopy measurement on the

selectively functionalized graphene layers which are produced by the nano-scale lithography with Atomic

Force Microcopy. To clarify the origin of the ferromagnetic signal, we measured XMCD measurement on the

C atoms in the locally functionalized graphene area by using element-specific XMCD-PEEM technique. The

significant XMCD signal obtained at C K edge clearly revealed that the ferromagnetic signal is originated from

the magnetic C atoms. By analyzing the dependence of XMCD spectra on the oxidizing condition, we could

approach the mechanism of the formation of ferromagnetic order in the graphene oxide layers.

B-377

HA-02

Measurement of interface Dzyaloshinskii-Moriya

Interaction energy density in various ferromagnetic and

heavy metal systems

Chun-Yeol You(a),(b)

(a)Department of Physics, Inha University, Korea

(b)Department of Emerging Materials Science, DGIST, Korea

Interfacial Dzyaloshinskii-Moriya Interaction (iDMI) has been intensively

investigated because of its potential applications to the future information storage

and/or logic devices and scientific importance. We measured the iDMI energy density

in various (HM,I)/FM/(HM,I) structures, where HM and I are heavy metals (W, Ta, Pt,

Ir) and insulator layers (AlOx, MgO), respectively. We used BLS (Brillouin Light

Scattering) to find non-reciprocal spin wave dispersion relations, which is proportional

to the iDMI energy density. Furthermore, we introduced another measurement method.

We found that it is possible to extract iDMI energy density from hysteresis loop

measurements for laterally asymmetry systems such as triangles with the additional

in-plane field. We found the new method has unique advantages compared with BLS or

domain wall velocity measurement methods. It is simpler because it can be done by

any kind of static hysteresis loop measurement, and the extracted value is well agreed

with the BLS measurement results. We will discuss and compare about BLS and

hysteresis loop measurements techniques for various inversion symmetry breaking

systems.

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HA-03

Magnetization Switching in Exchange-Coupled Systems

Takeshi SEKI(a),(b), Weinan ZHOU(a), Koki TAKANASHI(a)

(a)Institute for Materials Research, Tohoku University, Sendai, Japan (b)JST-PRESTO, Saitama, Japan e-mail: go-sai@imr.tohoku.ac.jp

A new route for reducing the switching field (Hsw) while maintaining the thermal stability of magnetization is indispensable for further increase in areal density of magnetic storage media. From the viewpoint of thermal stability of magnetization in nanoscale, L10-FePt is one of the candidate materials for the recording media because of its high uniaxial magnetic anisotropy (Ku). Thus, it is required that Hsw of L10-FePt is effectively reduced only when data are written into magnetic bits. We previously reported that spin wave excitation remarkably reduced Hsw for the exchange-coupled L10-FePt / Ni81Fe19 (Permalloy; Py) bilayer with in-plane magnetization [1-3]. From the practical point of view, however, such Hsw reduction should be done for a bilayer with an out-of-plane configuration of magnetic moments.

In this study, we exploit a nanodot of an exchange-coupled bilayer with a perpendicularly magnetized L10-FePt and a soft magnetic Py having a magnetic vortex. A low field switching technique is demonstrated by utilizing the vortex dynamics to switch the magnetization of L10-FePt [4].

Thin films were grown on an MgO (100) single crystal substrate with the stack of MgO subs. || Fe (1) | Au (60) | FePt (10) | Py (150) | Au (5) | Pt (3) (in nanometer) by employing a magnetron sputtering system and an ion beam sputtering system. The FePt layer was grown at 550ºC to promote the L10 ordering while the other layers were deposited at ambient temperature. We patterned the thin films into circular-shaped nanodots with a diameter of 260 nm. The micromagnetic simulation suggested that the magnetic vortex was formed in Py whereas L10-FePt had perpendicular magnetization. With no excitation of vortex dynamics, Hsw was obtained to be more than 8 kOe. On the other hand, we observed the significant Hsw reduction down to about 3 kOe when the vortex dynamics with unique spin wave modes was excited. We conclude that the vortex dynamics in Py effectively triggers the nucleation of reversed domains in L10-FePt, resulting in the low field switching of L10-FePt. [1] T. Seki et al., Nat. Commun., 4, 1726 (2013). [2] T. Seki et al., Appl. Phys. Lett. 103, 122403 (2013). [3] T. Seki et al., J. Phys. D: Appl. Phys. 49, 075002 (2016). [4] W. Zhou et al., Arxiv1601.05521.

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HA-04

High-frequency spin dynamics of a magnetic antivortex

Kristen S. Buchanan

Department of Physics, Colorado State University, Fort Collins, CO, United States

Magnetic vortices have been studied extensively in recent years because of their rich physics as

well as their potential for applications and other topological spin states, especially skyrmions, are also

attracting interest. In contrast, comparatively few experimental investigations have been conducted

on the magnetic antivortex (AV) spin configuration, in part because they are more difficult to create.

The AV, the topological counterpart of a magnetic vortex, involves spins that sweep in towards a

central core from two opposing directions and away in the other directions. It is a potentially

interesting configuration for magnonics devices since AV’s will form at cross-like intersections and

the spin configuration in these structures is such that the magnetization blends smoothly from the

intersection region into the wires, which should facilitate SW propagation. In this work, we show that

the AV state can be reliably created in micron-sized Permalloy nanostructures with a pound-key-like

shape by using shape anisotropy to control the reversal process [1], and we show experimental

measurements of the high-frequency spin dynamics of the magnetic AV’s in these structures, made

using micro-focus Brillouin light scattering (micro-BLS) [2]. Micro-BLS spectra, measured at

~250-nm spots at various locations on the patterned structures for samples in both the AV and

saturated configurations, show that the dynamics of an AV are more complex than those of a magnetic

vortex. Strong modes were detected in the 5-6 GHz range independent of the spin configuration and

spatial scans show that these modes are more closely associated with the microstrips than the

intersection; however, at lower frequencies, distinct dynamics were observed for the AV. Several of

the detected AV modes are close in frequency to azimuthal-like modes observed in micromagnetic

simulations and, furthermore, the simulations at the azimuthal spin wave frequencies show that

intersection spin state can influence the dominant wavevector in the structure legs, which is of

potential interest for magnonics devices since many proposed devices require high wavenumber

excitations. This work was supported by DOE-BES ER46854.

[1] M. Asmat-Uceda, L. Li, B. Shaw, A. Haldar, and K. S. Buchanan, J. Appl. Phys. 117, 173902

(2015).

[2] G. A. Riley, H. J. Liu, M. A. Asmat-Uceda, A. Haldar, and K. S. Buchanan, Phys. Rev. B 92,

064423 (2015).

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HA-05 Growth of flexible NiFe2O4 thin films via Van der Waal

heteroepitaxy

Yugandhar Bitla(a) and Ying-Hao, Chu(a)(b)(c)

(a) Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

(b) Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (c) Department of Electrophysics, National Chiao Tung University, Hsinchu 30010,

Taiwan E-mail: yugibitla@gmail.com

The growth of high quality single crystalline NiFe2O4 (NFO) thin films has been

seriously pursued recently as a prime candidate for sensors, spin filter devices, circuit elements, memory, and magnetoelectric composites1-2. This is due to the fact that inverse spinel NFO has high Curie temperature, high saturation magnetization, moderate magnetostriction, large exchange splitting and a wide band-gap. In this work, we demonstrate the epitaxial growth of NFO(111) thin films on flexible and transparent muscovite mica substrate via Van der Waal heteroepitaxy using pulsed laser deposition technique. Detailed structural and magnetic characterizations revealed that NFO thin films retain the inverse spinel structure and exhibit room temperature ferrimagnetism. The NFO was further integrated with a ferroelectric material for the realization of magnetoelectric phenomenon at microwave frequencies necessary for the electric field tunable microwave phase shifters and band-pass filters. Therefore, our approach not only offers great opportunities for next generation reconfigurable RF/microwave communication systems, Spintronics, magnetic field sensors, etc. but also provide a framework for realizing compact, light-weight, and ultralow power electronics and microwave devices.

[1] Cullity B D, Graham C D (2009), Introduction to Magnetic Materials, 2nd ed. Hoboken, NJ, USA: IEEE/Wiley [2] U. Lüders, A. Barthélemy, M. Bibes, K. Bouzehouane, S. Fusil, E. Jacquet, J.-P. Contour, J.-F. Bobo, J. Fontcuberta, and A. Fert, Adv. Mater. 18, 1733 (2006).

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HA-06

Magnetic properties of RE:ZnO (RE=Sm,Eu,Gd,Dy,Ho,Er) thin films grown by

pulsed-laser deposition

Fang-Yuh Lo(a), Tsung-Chun Hsieh(a), Tzu-Lung Tseng(a), Kai-Chieh Chou, Yi-Chieh Ting(a), Yu-Ting Yeh(a), Wen-Tze Huang(a), Yung-Yuan Hsu(a), and

Ming-Yau Chern(b)

(a) Department of Physics, National Taiwan Normal University, 11677 Taipei City, Taiwan

(b) Department of Physics, National Taiwan University, 10617 Taipei City, Taiwan e-mail: fangyuhlo@ntnu.edu.tw

Zinc oxide thin films doped with rare-earth elements (RE), such as Sm, Eu, Gd, Dy, Ho, and Er, were fabricated on c-oriented sapphire substrate at 550 oC under oxygen partial pressure of 3×10-1 mbar by pulsed-laser deposition with doping concentration of 5 atomic percent. Structural, optical, and magnetic properties of Gd:ZnO thin films were studied.

X-ray diffraction (XRD) revealed incorporation of RE into ZnO host matrix without secondary phase, where Gd- and Dy-doped ZnO thin films have the best crystal quality.

Defects identified by photoluminescence (PL) spectroscopy were zinc vacancies and zinc interstitials for all thin films, and the 4f subband transitions of RE elements were not observed.

Magnetic investigations with a superconducting quantum interference device (SQUID) showed paramagnetic magnetization loops for all thin films, but Ho-doped ZnO exhibited blocking-type of ordering below T = 150 K.

-40 -30 -20 -10 0 10 20 30 40-100

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20

40

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ZnO Gd:ZnO Dy:ZnO Ho:ZnO Er:ZnO

m (e

mu

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H (kOe)0 30 60 90 120 150 180 210 240 270 300

0.4

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0.9

m (e

mu

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T (K)

(b) Ho:ZnOH = 100 Oe

FC ZFC

Figure 1 (a) Magnetization loops of RE-doped ZnO thin films measured at T = 5 K.

(b) Field-cooled (FC) and zero-field-cooled (ZFC) curves of Ho:ZnO thin films.

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HB-01

Deposition and Etch Process Equipment Capabilities for Embedded STT MRAM

Mahendra Pakala

Applied Materials, Sunnyvale, California, USA e-mail: Mahendra_pakala@amat.com

Improvements in PVD Deposition and Etching of perpendicular MTJ stacks, to

enable embedded STT MRAM are presented. Some developments in area of high

temperature data retention and barrier reliability are highlighted using electrical results

of integrated MTJ arrays with cell pitch of 130nm to 200nm. Equipment capabilities

used to achieve these results are described, including volume manufacturing

considerations. Further scaling in terms of etching of dense MTJ arrays are also

discussed, using the novel etch process

developed at Applied Materials [1]. Critical

to device reliability is having a high

breakdown voltage of the MgO barrier. By

optimizing the RF MgO deposition process,

high BDV > 1.5V was obtained for RA ~

10Ohms-um2 bottom pinned perpendicular

MTJ Stack as shown in Fig. 1. In addition,

by using a novel etch process, MTJ arrays

with CD of 40-60nm and with <200nm pitch

were fabricated that can withstand > 350C

BEOL process temperatures as shown in

Figure 2. Finally MTJ arrays with average

coercivity of > 3kOe were demonstrated

indicating strong PMA achieved for high

temperature data retention. [1] C. Park et al., IEDM15-664 (2015) [2]L. Xue et al., IEE Trans Magn., vol. 51 4401503 (2015)

Figure 1. Breakdown voltage for barrier

prepared by RF MgO compared to Mg+Ox

process. Insert shows TMR performance for

the same 2 process

Figure 2. TMR% of MTJ arrays

(CD:50nm/Pitch: 200nm) as function of post

etch bake temperature

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HB-02

Initialization-free multilevel states driven by spin-orbit torque Switching

Kuo-Feng Huang,(a) Ding-Shuo Wang,(a) Hsiu-Hau Lin,(b) and Chih-Huang

Lai(a)*

(a)Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan

(b)Department of Physics, National Tsing Hua University, Hsinchu, 300, Taiwan

Spin-orbit-torque magnetic random access memory (MRAM) has been intensively investigated recently because of its excellent properties but the 3-terminal setup casts shadows on shrinking the cell size for practical devices.

Demonstrated in a variety of non-volatile memories, multilevel storage is an effective remedy to overcome the obstruction. However, initialization process for achieving multilevel storage is often inevitable and costs prolonged write latency and wasted power consumption. By engineering multi-domain formation in Co/Pt multilayers, we demonstrate how initialization-free multilevel storage can be achieved by spin-orbit torque switching. With the appropriate number of repeated Co/Pt layers, the multi-domain states become energetically favorable and can be manipulated with precision by spin-orbit torques. It is rather remarkable that, by modulating the writing pulse conditions, we can precisely control the final magnetization states, independent of the initial configurations. The initialization-free multilevel memory advances the spin-orbit-torque MRAM to higher storage density for practical applications.

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HB-03

Electrical detection of coherent spin precession in InAs 2DEG

Joonyeon Chang

Center for Spintronics,

Post-Si Semiconductor Institute (PSI)r Korea Institute of Science and Technology (KIST)

The spin-orbit interaction in two dimensional electron systems provides an

exceptionally rich area of research. Coherent spin precession in a Rashba effective

magnetic field in the channel of a spin field effect transistor and the spin Hall effect are

the two most compelling topics in this area. We combine these effects to provide a

direct demonstration of the ballistic intrinsic spin Hall effect and to demonstrate a

technique for an all-electric measurement of the Datta–Das conductance oscillation,

that is, oscillations in the source-drain conductance due to spin precession. Our hybrid

device has a ferromagnet electrode as a spin injector, and a spin Hall detector. Results

from multiple devices with different channel lengths map out two full wavelengths of

the Datta–Das oscillation. We also use the original Datta–Das technique with a single

device of fixed length and measure the channel conductance as the gate voltage is

varied. Our experiments show that the ballistic spin Hall effect can be used for efficient

injection or detection of spin polarized electrons, thereby enabling the development of

an integrated spin transistor. In the talk, I will briefly introduce the background of

semiconductor spintronics followed by spin field effect transistor and spin Hall device

built on InAs 2DEG structure with high spin orbit interaction.

B-385

HB-04

Photo-Spin-Voltaic Effect

David Ellsworth(a), Lei Lu(a), Jin Lan(b)(c), Houchen Chang(a), Peng Li(a), Zhe Wang(c), Jun Hu(b), Bryan Johnson(a), Yuqi Bian(a), Jiang Xiao(c)(d),

Ruqian Wu(b) (c), and Mingzhong Wu(a)*

(a)Department of Physics, Colorado State University, Fort Collins, CO 80523, USA. (b)Department of Physics and Astronomy, University of California, Irvine, CA 92697,

USA. (c)Department of Physics, Fudan University, Shanghai 200433, China.

(d)Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai, 200433, China.

The photo-voltaic effect, discovered by Becquerel in 1839, has made a rather

profound impact on the advancement of modern society. The effect typically occurs

in semiconductors and involves photon-driven excitation of electrons from a valence

band to a conduction band. In a region such as a p-n junction that has a built-in electric

field, the excited electrons and holes diffuse in opposite directions, resulting in an

electric voltage. This presentation reports that a spin voltage can be created by

photons in a non-magnetic metal that is in close proximity to a magnetic insulator, a

photo-spin-voltaic effect. The experiments used normal metal/magnetic insulator

heterostructures where the normal metal was a nm-thick Pt layer and the magnetic

insulator (MI) was an Y3Fe5O12, doped Y3Fe5O12, or BaFe12O19 film with a thickness

in the 10-105 nm range. When light illuminates the Pt film, photons with appropriate

energy excite electrons in the occupied bands to the unoccupied bands. For the Pt

atomic layers in close proximity to the MI, the efficiency of the photon-driven electron

excitation is different for electrons in different spin channels. This efficiency

difference, together with the difference in the diffusion of the excited electrons and

holes, gives rise to a spin voltage near the interface and a corresponding pure spin

current across the Pt thickness. Such spin currents can produce a measurable electric

voltage in the Pt film via the well-known inverse spin Hall effect. This new

phenomenon is an analogy to the photo-voltaic effect in semiconductors, but engages

spin-dependent photon-driven electron excitation.

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HB-05

Amorphous carbon: a smart material for spintronics

applications

H. S. Hsu* Department of Applied Physics, National Pingtung University, Pingtung 900,

Taiwan, Republic of China

Email: hshsu@mail.nptu.edu.tw

The carbon-based material has been identified as a candidate material for

semiconductor applications and has renewed interest in its electrical, optical and magnetoelectronic properties. Thin films of amorphous carbon(a-C) are amorphous semiconductors with a mixture of graphite–like sp2 and diamond-like sp3 bond characteristics; tuning of the sp2/sp3 ratio, makes them superior with many degrees of freedom over the conventional group ІⅤ amorphous semiconductors. Especially, recently developments in spintronic materials have drawn attention to the magnetoelectronic properties. The combination of ferromagnetic materials and carbon will produce interesting properties.

This talk will address some examples: The observation of a considerable intrinsic positive magnetoresistance (PMR) effect in Co-doped a-C films [1]. The kind of PMR effect is bias dependence and its ratio reaches a peak at a particular voltage. A phenomenological model related to orbital Zeeman splitting has been proposed to describe the resistance, which is controlled by voltage and magnetic field. On the other hand, we also observe that Co clusters in a-C films induce sizeable magnetic circular dichroism (MCD) effects [2], which is contributed by the hybridization effect at the Co/C interface. Several applications such as electric filed control magnetization by inserting a-C layers will also be presented.

[1] H. S. Hsu*, P. Y. Chuang, J. H. Zhang, S. J. Sun, H. Chou, H. C. Su, C. H. Lee, J. Chen, and J. C. A. Huang,“ Observation of bias-dependent low field positive magneto-resistance in Co-doped amorphous carbon films”, Appl. Phys. Lett. 96, 262504 (2010). [2]H. S. Hsu*, P. E. Liu, C. W. Chang, S. J. Sun, C. H. Lee, H. C. Su, Y. Y. Chin, H. J. Lin, C. T. Chen and M. J. Huang. “Tunable interfacial magnetic-optical properties of Co doped amorphous carbon film induced by charge transfer after acid treatment.” Carbon 77, 398 (2014).

B-387

Overview of Electric Vehicle Machines – From

Tesla to Tesla, and Beyond

Topics: EM2-Electric Machines Applications

Abstract—Starting from the rotating magnetic field theory developed by Nikola Tesla in 1882, the

induction machine has become the most popular electric machine for over a century. Actually, the Tesla’s AC

Induction Motor is dubbed one of the ten greatest discoveries of all time. This popularity has been extended to

the latest Tesla Motors which has set a new world speed record for production electric vehicles (EVs).

Meanwhile, the permanent-magnet (PM) brushless machines are superseding the induction machine because

of their high efficiency and high power density. In order to fulfill the ever increasing demand on electric

propulsion, innovation of electric machines accelerates. For instance, the stator-PM machines combine the

merits of both PM brushless and switched-reluctance machines to offer energy-efficient robust operation; the

vernier PM in-wheel machines incorporate the vernier effect into the PM brushless machines to provide

low-speed high-torque direct-drive operation; and the advanced magnetless machines adopt innovative

topologies to compensate the reduction of torque and power densities due to the absence of PM material.

Increasingly, the development of electric machines has been expanded to incorporate the heat engine for

hybrid propulsion. Rather than using the planetary-geared machine system to perform power split for

electronic continuously variable transmission (ECVT), the double-rotor machine system is developed to

achieve gearless ECVT, and the magnetic-geared machine system is proposed to achieve ECVT without

physical gearing or brushes. In this paper, various electric machines and machine systems for electric and

hybrid vehicles will be discussed, with emphasis on the challenges and opportunities of those emerging

machine topologies.

EV Machine Requirements

Electric machines are one of the core technologies for EVs and hybrid EVs (HEVs), which convert the

limited on-board electrical energy to the desired vehicular mechanical motion. The corresponding

requirements are much more stringent than that for industrial applications [1],[2]:

High torque and power densities.

High torque capability for electric launching and hill climbing.

K.T. Chau

Department of Electrical and Electronic Engineering, The University of Hong Kong (ktchau@eee.hku.hk)

HC-01

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High efficiency over wide torque and speed ranges.

Wide-speed operating range for low-speed creeping and high-speed cruising.

Wide constant-power operating capability.

High intermittent overload capability for overtaking.

High reliability and robustness for vehicular environment.

Publicly acceptable cost.

When electric machines need to work with engines for HEVs, there are additional requirements:

High-efficiency energy generation over wide-speed operation.

Good voltage regulation over wide-speed generation.

Capable of integrating with the engine.

EV Machines for Electric Propulsion

The classification of EV machines for electric propulsion is depicted in Fig. 1 where the bold and colored ones have been applied to EVs, including the PM DC, series DC, shunt DC, separately excited DC, cage-rotor induction, PM synchronous (PMSyn), PM brushless DC (PMBDC) and switched reluctance (SR) machines. Essentially, EV machines are classified as the commutator type which has a commutator and carbon brushes, and the commutatorless type which has no commutator. In recent years, the development trend is to develop different types of commutatorless machines [3], especially the class of doubly-salient machines and the class of vernier machines.

Fig. 1. Classification of EV machines for electric propulsion

There are many kinds of doubly-salient machines. Their key feature is the presence of salient poles in both the stator and rotor. The SR machine is the simplest kind of doubly-salient machines. When incorporating PMs into the stator of doubly-salient machines, the stator-PM machines are derived [4]. Since the rotor has no PMs or windings, they can retain high torque and power densities while offering mechanical simplicity and robustness, which are desirable for vehicular operation. Due to different locations of the PMs, these stator-PM machines can be specified as the doubly-salient PM (DSPM), flux-reversal PM (FRPM) and flux-switching PM (FSPM) machines. By adding DC field windings and magnetizing windings in the stator for flux control, they can be further specified as the hybrid-excited PM (HEPM) and flux-mnemonic PM (FMPM) versions, respectively, which are collectively termed the flux-controllable PM (FCPM) versions. When all PM poles are replaced with DC field windings, the doubly-salient DC (DSDC), flux-reversal DC (FRDC) and flux-switching DC (FSDC) machines are derived, which are advanced magnetless machines that can offer very

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low cost and flexible flux control. By properly selecting the numbers of salient poles in the stator and rotor, the vernier machines can utilize

the vernier effect to amplify the output torque while stepping down the speed, which is very desirable for low-speed high-torque direct-drive vehicles. They consist of the vernier PM (VPM) and vernier reluctance (VR) machines. The VPM machines can be rotor-PM or stator-PM, depending on the location of PMs. The rotor-PM VPM machine is most mature, and loosely termed the VPM machine [5], while the stator-PM VPM machine is also termed the vernier hybrid machine [6]. Without using PM excitation, the VR machines are structurally similar to the SR machine, but they operate differently. Because of their inherently low power factor, the VR machines can equip with an additional field winding, either DC or AC, in the stator to form the doubly-fed VR (DFVR) machine [7]. The VR and DFVR machines are also classified as advanced magnetless machines.

All EV machine topologies can readily be extended from the radial-flux morphology to other morphologies such as the axial-flux and transverse-flux morphologies [8]. The axial-flux morphology possesses the merits of higher torque and power densities than its radial-flux counterpart, but suffers from the drawback of axial force between the stator and rotor. The transverse-flux morphology can offer the highest torque density over its counterparts, but the corresponding machine structure is very complicated which hinders its practicability.

EV Machines for Hybrid Propulsion

The classification of EV machine systems for hybrid propulsion is depicted in Fig. 2, where the bold and colored ones have been applied to HEVs including the integrated-starter-generator (ISG) system is for the micro HEV and mild HEV, and the ECVT system is for the full HEV and plug-in HEV (PHEV) [9]. The ISG system aims to offer not only the conventional features of engine cranking and electricity generation, but also the hybrid features of idle stop-start, regenerative braking and power assistance. Consequently, the machine designs are very demanding [10]. The ECVT system aims to offer continuously variable transmission from the engine to the wheels in an electronic way, hence achieving optimal fuel economy while retaining all hybrid features including the idle stop-start, regenerative braking and power assistance plus the unique feature of electric launch. Among three main types of ECVT systems: the planetary-geared ECVT (PG-ECVT), double-rotor ECVT (DR-ECVT) and magnetic-geared EVT (MG-ECVT), the PG-ECVT system is exclusively used for the buyable full HEV and PHEV [11]. However, this PG-ECVT system suffers from the fundamental drawback of planetary gearing such as the transmission loss, gear noise and lubrication requirement. In order to get rid of the planetary gear, the gearless DR-ECVT system has been proposed, which utilizes the double-rotor machine to replace the planetary gear for power split [12]. However, this DR-ECVT system suffers from the drawback of using slip-rings and carbon brushes to extract the energy from the inner rotor such as the reliability problem and maintenance requirement. By replacing the planetary gear with the magnetic planetary gear or magnetic coaxial gear, the MG-ECVT system can retain the merits of magnetic gearing and prevent from using slip-rings and carbon brushes so as to achieve pseudo-gearless and brushless [13]. However, this MG-ECVT system is so complicated that it demands precision manufacturing.

Fig. 2. Classification of EV machine systems for hybrid propulsion

Challenges and Opportunities

The stator-PM machines have high opportunities for EVs because they can solve two fundamental

problems of those PM brushless brushless machines, including the PMSyn and PMBDC machines. Namely,

there are no PMs in the rotor, which can avoid the problem on mounting PMs on the high-speed rotor and

hence improving the mechanical integrity; and all PMs are located in the stator, which can enhance the cooling

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arrangement and hence improving the thermal stability of PMs. Those major types of stator-PM machines for

electric propulsion, namely the FSPM, FRPM, DSPM and FCPM, are qualitatively compared as summarized

in Table 1. Since the FCPM machines are the flux-controllable versions of the three basic stator-PM machines,

they consist of many members such as the HE-FSPM, FM-FSPM, HE-FRPM, FM-FRPM, HE-DSPM and

FM-DSPM.

Concerning the torque and power densities, the FSPM machine is most preferable because of the

flux-focusing arrangement. Meanwhile, the power density of the FCPM machines is degraded due to the use of

additional DC field winding or magnetizing winding. Nevertheless, the developed torque, especially for

electric launch or overtaking of EVs, can be temporarily boosted by instantaneous air-gap flux strengthening.

Since the FCPM machines have the definite merit of flexible air-gap flux control, they can achieve higher

efficiency than that of the basic FSPM, FRPM and DSPM machines. Concerning controllability, the FCPM

machines are much better than those singly-fed stator-PM machines. As the PM material is relatively delicate,

the PM immunity to accidental demagnetization and mechanical abuse are a key performance index for PM

machines. Among those stator-PM machines, the FRPM machine has a relatively weak PM immunity because

their PMs are mounted on the surfaces of stator poles so that they are prone to be partially demagnetized under

high armature field or high temperature operation, and vulnerable to be physical damaged under severe

vibration. Concerning robustness and manufacturability, the DSPM machine is most preferable because its

structure is simplest in both the stator and rotor, leading to be highly robust and easily manufacturing. In

contrast, the FCPM machines have to install two sets of windings (armature and field windings) in the stator,

which inevitably degrades their manufacturability. Concerning maturity, the DSPM machine is most mature as

it has been developed for over two decades. Then, the FSPM and FRPM machines are becoming mature, which

have been developed for over a decade. The FCPM machines are recently derived from the singly-fed

stator-PM machines so that they are relatively immature.

The VPM machines have the definite advantage of low-speed high-torque operation, which is essential for

in-wheel direct-drive application. When adopting the conventional inner-rotor structure, the VPM machines

need a mechanism to transmit the inner-rotor torque to the wheel, which definitely degrades their practicability.

On the contrary, when adopting the outer-rotor structure, the VPM machines do not need any mechanism to

transmit the outer-rotor torque to the wheel as the outer rotor is directly coupled with the wheel rim. Moreover,

the inner stator of the outer-rotor structure can be fully utilized to accommodate the armature winding and the

optional DC field winding. Because of the fact that most EV manufacturers do not prefer to use the in-wheel

direct drive, the development of VPM machines for electric propulsion is much slower than expected. With

ever increasing demand on higher performance and better stability, it is anticipated that the VPM machines will

be popular for in-wheel direct-drive EVs.

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Table 1. Evaluation of stator-PM motor drives for EVs FSPM FRPM DSPM FCPM Torque density High Good Medium High

Power density High Good Medium Medium

Efficiency Good Good Good High Controllability Medium Medium Medium Superb

PM immunity Good Weak Medium Good

Robustness Medium Medium High Medium

Manufacturability Medium Medium Easy Hard

Maturity Medium Medium High Low

Because of the high price and fluctuating supply of rare-earth elements for PM materials, the advanced

magnetless machines will be the core for EVs desiring high cost-effectiveness. The major types of advanced

magnetless machines that are viable for electric propulsion are the DSDC, FSDC, VR, DFVR, and axial-flux

magnetless (AFM) are compared as summarized in Table 2. It should be that the AFM machines refer to the

axial-flux versions of those viable radial-flux magnetless machines such as the DSDC and FSDC machines.

Table 2. Comparison of potentiality of advanced magnetless motor drives

FSDC DSDC VR DFVR AFM

Torque density High Good High High Superb Power density High Good Low Fair Superb Efficiency High High Fair High High Controllability High High Fair High High Power factor Fair Fair Low Fair Fair Material cost Fair Fair Low Fair Fair Robustness Fair Fair High Fair Low Manufacturability Fair Fair Easy Fair Hard

Maturity Fair Fair High Low Low

Concerning the torque and power densities, the AFM machines are most preferable as they can fully utilize

the material for torque production. Since the FSDC machine exhibits bipolar flux linkage, it offers higher

torque and power densities than the DSDC machine. While both the VR and DFVR machines have the vernier

effect, they can offer high torque density for low-speed operation. Concerning the efficiency, controllability

and power factor, the doubly-fed magnetless machines having the capability of field control, namely the FSDC,

DSDC, DFVR and AFM, can achieve better performances than the singly-fed VR machine. On the contrary,

concerning the material cost, robustness, manufacturability and maturity, the VR machine can offer better

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performances than those doubly-fed magnetless machines. In particular, the AFM machines desire the

double-stator or double-rotor structure, which significantly deteriorates their robustness, manufacturability

and maturity. Meanwhile, the FSDC and DSDC machines are considered as the most prominent magnetless

alternatives. Both the DFVR and AFM machines are relatively most immature.

In the foreseeable future, it is anticipated that both EVs and HEVs will coexist in the market. Among all

kinds of HEVs, the full HEV and PHEV are most attractive. As the ECVT is their core technology, the

MG-ECVT system exhibits high opportunities for future HEVs. Compared with other ECVT systems, the

MG-ECVT system has the definite advantages of pseudo-gearless and brushless, which can significantly

improve the system efficiency, power density and operability for hybrid propulsion. The key challenges of this

system are mainly the high initial cost due to the utilization of much PM materials and the complex structure

which desires precision manufacturing. Being fueled by continual development of new PM materials and

high-precision manufacturing techniques, this MG-ECVT system is highly promising for hybrid propulsion in

near future.

Acknowledgment

This work was supported by a grant (Project No. 17200614) from the Hong Kong Research Grants Council,

Hong Kong Special Administrative Region, China.

References

[1] Z.Q. Zhu and D. Howe, “Electrical machines and drives for electric, hybrid and fuel cell vehicles,” Proceedings of IEEE, vol. 95, 2007, pp. 746-765.

[2] K.T. Chau and W. Li, “Overview of electric machines for electric and hybrid vehicles,” International Journal of Vehicle Design, vol. 64, 2014, pp. 46-71.

[3] K.T. Chau, C.C. Chan, and C. Liu, “Overview of permanent-magnet brushless drives for electric and hybrid electric vehicles,” IEEE Transactions on Industrial Electronics, vol. 55, 2008, pp. 2246-2257.

[4] C. Liu, K.T. Chau, J.Z. Jiang, and S. Niu, “Comparison of stator-permanent-magnet brushless machines,” IEEE Transactions on Magnetics, vol. 44, 2008, pp. 4405-4408.

[5] J. Li, K.T. Chau, and W. Li, “Harmonic analysis and comparison of permanent magnet vernier and magnetic-geared machines,” IEEE Transactions on Magnetics, vol. 47, 2011, pp. 3649-3652.

[6] E. Spooner and L. Haydock, “Vernier hybrid machines,” IEE Proceedings - Electric Power Applications, vol. 150, 2003, pp. 655-662.

[7] S. Taibi, A. Tounzi, and F. Piriou, “Study of a stator current excited vernier reluctance machine,” IEEE Transactions on Energy Conversion, vol. 21, 2006, pp. 823-831.

[8] K.T. Chau, Electric Vehicle Machines and Drives – Design, Analysis and Application. Wiley-IEEE Press, 2015.

[9] K.T. Chau and C.C. Chan, “Emerging energy-efficient technologies for hybrid electric vehicles,” Proceedings of IEEE, vol. 95, 2007, pp. 821-835.

[10] C. Liu, K.T. Chau, and J.Z. Jiang, “A permanent-magnet hybrid brushless integrated starter- generator for hybrid electric vehicles,” IEEE Transactions on Industrial Electronics, vol. 57, 2010, pp. 4055-4064.

[11] M. Kamiya, “Development of traction drive motors for the Toyota hybrid system,” IEEJ Transactions on Industry Applications, vol. 126, 2006, pp. 473-479.

[12] M. Hoeijmakers and J. Ferreira, “The electric variable transmission,” IEEE Transactions on Industry Applications, vol. 42, 2006, pp. 1092-1100.

[13] L. Jian and K.T. Chau, “A novel electronic-continuously variable transmission propulsion system using coaxial magnetic gearing for hybrid electric vehicles,” Journal of Asian Electric Vehicles, vol. 7, 2009, pp. 1291-1296.

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High-Efficiency Magnetic Gear and Developing Magnetic-Geared Motor

Kenji Nakamura, Osamu Ichinokura

Graduate School of Engineering, Tohoku University, Sendai, Japan e-mail: nakaken@ecei.tohoku.ac.jp

Magnetic gears can transmit torque without any mechanical contacts. Hence, they

have low vibration, no wear and fatigue, which offer maintenance-free operation. Various kinds of magnetic gears have been introduced in previous papers and patents. Among them, a flux-modulated type magnetic gear, which consists of an inner and outer rotor with surface–mounted permanent magnets, and ferromagnetic stationary parts which are called pole–pieces, is attracting interest since the torque density is higher than the other magnetic gears [1].

This paper presents the optimum geometry and position of the pole–pieces based on three-dimensional finite element analysis and experiment, in order to improve torque and efficiency of the flux-modulated type magnetic gear.

Fig. 1 shows specifications of the improved magnetic gear. The maximum torque increases from 9.4 N·m to 13.6 N·m and the maximum efficiency is also improved from 85% to 99% as shown in Fig. 2.

Furthermore, this paper also presents an in-wheel magnetic-geared motor, which is now in development by a collaborative research with a company. The possibility of the proposed magnetic-geared motor is demonstrated by experiments.

Inner pole-pairs 3

Outer pole-pairs 31

Number of pole-pieces 34

Gear diameter 170 mm

Axial length 10 mm

Inside air gap 1.5 mm

Outside air gap 0.5 mm

Magnet material Nd-Fe-B

Residual flux density 1.25 T

Coercive force 975 kA/m

Fig. 1 Improved magnetic gear.

0 50 1000

5

10

15

Time (sec.)0 50 100

Time (sec.)

13.6 N·m

9.4 N·m

1.45 times

0 1000 2000 30000

100

200

300

400

500

0

20

40

60

80

100

Input speed (r/min.)

Inpu

t an

d ou

tput

pow

ers

(W)

Eff

icie

ncy

(%)

InputOutputEfficiency

0 1000 20000

100

200

300

400

500

0

20

40

60

80

100

Input speed (r/min)

Inpu

t and

out

put p

ower

s (W

)

Eff

icie

ncy

(%)

InputOutputEfficiency

99%

Fig. 2 Torque (top) and efficiency (bottom) characteristics before (left) and after (right) improvements.

[1] K. Atallah and D. Howe, IEEE Trans. Magn., 37, 2844 (2001).

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On the Use of the Frozen Permeability Method for Torque Separation in Synchronous Machines

David G. Dorrell Discipline of Electrical, Electronic and Computer Engineering, Faculty of Engineering

University of KwaZulu-Natal, Howard College, Durban, 4041, South Africa

d.g.dorrell@gmail.com

This digest explores the use of the frozen permeability method to decompose the

torque in a synchronous machine into the excitation and reluctance components.

Synchronous machines can obviously be wound field turbo-generators but increasingly

brushless permanent magnet synchronous machines are being used in electric vehicles.

These are often interior permanent magnet machines with considerable reluctance

torque. Under high torque conditions the machines are highly saturated. This digest

explores the difference torque calculation methods that can be used in the frozen

permeability method.

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Multiphysics Analysis for Traction Motors Considering Electromagnetics, Noise, Vibration and

Harshness

Chien-Hsing Li and Min-Fu Hsieh Department of Systems and Naval Mechatronics Engineering, National Cheng Kung

University, Tainan, Taiwan

mfhsieh@mail.ncku.edu.tw

This paper presents the multiphysics analysis covering electromagnetics, Noise,

Vibration and Harshness (NVH) for interior permanent magnet (IPM) motor applied to

electric vehicle (EV) tractions. The IPM motor takes advantage of reluctance torque

but may suffer potential NVH problems. The electromagnetic analysis is first

conducted for the IPM motor such that the output torque, speed, and the flux density in

the air gap can be calculated and then the force density acting on air gap can be

obtained. Because the rotor and stator are considered to be structurally flexible, and

therefore an iterative analysis for the change of air-gap length due to the

electromagnetic/centrifugal forces that cause structural deformation is conducted. This

would consequently results in vibrations and noises. The objective of this paper is to

develop a method that helps machine designers identify the performance limit of the

machine when considering factors of noise and vibration. Therefore, a tradeoff

between the electromagnetic performance and mechanical characteristics can be

achieved.

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