Control of Magnetism in Prussian Blue Analogue Films

Mark W. Meisel, University of Florida, DMR 0701400

Control of the magnetic properties of synthetic materials is one of the reasons molecule-based magnets are of interest, and Prussian blue analogues (PBAs) are a prominent example.

By controlling the growth of PBA hetero-structured films, the magnetism can be photocontrolled up to 70 K, and the effect arises from the presence of the interface [1].

Systematic studies of the properties of NiCr PBA thin, thick, and spin-cast films have provided an understanding of the origin of the anisotropic magnetic response [2].

Since film-based processing is commonly employed in device fabrication, these two discoveries provide crucial insight needed for the design of PBA-based devices.

[1] D.M. Pajerowski et al., JACS 132 (2010) 4058.[2] D.M. Pajerowski et al., arXiv:1006.3801.

0 20 40 60 800

5

10

15Light state

(1

0-5 e

mu

/cm

2)

Temperature (K)

Dark state

0 1 26.5

7.0

7.5

8.0

T = 60 K

Time (hours)

Light on

0 20 40 60 800.0

0.2

0.4

0.6

0.8

1.0

Single phase

Temperature (K)

MA

X

Heterostructure

Heterostructured ABA thin films of two Prussian blue analogues, where A is a NiCr ferromagnet (Tc ~ 70 K) and B is a photoinducible CoFe ferrimagnet (Tc ~ 20 K), have been made for the first time and allow the magnetism to be decreased by irradiation with white light and increases the photocontrol from 20 K to 70 K.

This interdisciplinary research builds upon our long-standing intramural (UF Physics-Chemistry and NHMFL High-B/T Lab) and international (Centre of Low Temperature Physics, Košice, Slovakia) collaborations. The PI was awarded Doctor honoris causa degree from Pavol Jozef Šafárik University, Košice, Slovakia.

The training of graduate and undergraduate students involves hands-on laboratory experiences and visits to national (e.g. ORNL and NHMFL) and international facilities and meetings.

The PI embraces Outreach Activities and his recent work focuses on K-8 teacher/student experiences involving “matter”. Elements of his work were used by the Florida PROMiSE Progam, and the PI is a developer and faculty participant.

Other NSF grants providing collaborative support:Daniel R. Talham, UF Chem (DMR-1005581), UF Physics Summer REU (DMR-0851707), andNHMFL (DMR-0654118).

Department of PhysicsDepartment of Chemistry

Meisel Group Summer 2010: (left to right) Alex Sincore, NHMFL REU student from UF; Anne Ziegler, UF Physics REU student from Univ. of St. Thomas; Mark Meisel, PI; Marcus Peprah, UF grad student; Elisabeth Knowles, UF grad student; Yitzi Calm, UF grad student. Absent: Donovan Thompson, NHMFL REU student from Georgia Southern Univ., Pedro Quintero, UF grad student, Daniel Pajerowski, NSF-EAPSI Fellow.

Daniel M. Pajerowski, PhD 2010, UF. Thesis: Magnetism in Nanostructures of Prussian Blue Analogues. Summer 2010: NSF-EAPSI Fellow.Fall 2010: NRC Postdoctoral Fellow at NIST.(Photo near Los Alamos, NM, during 2008 LANSCE Summer School.)

Model of Chemical Reactions: Cookie Sheet & Poker Chips!Meisel leads discussion during Duval (Jacksonville) PROMiSE K-8 Teachers Outreach Program, designed to enhance the science knowledge of the participants.

Control of Magnetism in Prussian Blue Analogue Films

Mark W. Meisel, University of Florida, DMR 0701400