Antiferromagnetic coulpling in spintronicsAntiferromagnetic coulpling in spintronics

Tomas Jungwirth

Univ. of Nottingham, UK

Institute of Physics ASCR & Charles Univ., Czech Rep.

Hitachi and Univ. Cambridge, UK& Japan

Politecnico di Milano, Italy

Univ. of California, Berkeley

Institut de Ciencia de Materials de Barcelona, Spain

Giant magnetoresistance (GMR) multilayers: the dawn of spintronics

Fert, Grünberg, et al. 1988Nobel Prize 2007

Antiferromagnetic arrangement of a ferromagnetic multilayer at B=0

FM

FM

FM

FM

FM

FM

Soft FM

Hard FM

Soft FM

Hard FM

Fixed FM AFM

Soft FM

Fixed FMAFM

Soft FM

1. AFM coupling between FMs at B=0

3. One FM pinned by AFM material

Writing information in spin-valve: towards spintronic memory (MRAM)

2. One FM flips harder than the other FM

Fixed FM

NM

AFM

Soft FM

Towards reliable switching of a particular MRAM bit

Fixed FMAFM

FM

FM

Toggle switching first commercial MRAMs

“Synthetic AFM“

Ie

Ie

Fert, Grünberg, et al. 1988Nobel Prize 2007

Read-out: Giant magnetoresistance (GMR)

M

Kelvin, 1857

Ie

Read-out: Anisotropic magnetoresistance (AMR)Spintronic effect 150 years ahead of time

M

Ie

Kelvin, 1857

Read-out: Anisotropic magnetoresistance (AMR)Spintronic effect 150 years ahead of time

Ohmic AMR

Magnetization-orientation-dependent scatteringRelativistic spin-orbit coupling

Kelvin, 1857

Ohmic GMR

Spin-channel-dependent scatteringNon-relativistic

Fert, Grünberg, 1988

Tunneling magnetoresistance (TMR)

MRAM

Spin-channel-dependent tunneling DOSNon-relativistic

Julliere 1975, Moodera et al., Miyazaki & Tezuka 1995

Tunneling anisotopic magnetoresistance (TAMR)

Gould, TJ et al. PRL ‘04

Magnetization-orientation-dependent tunneling DOSRelativistic spin-orbit coupling

“Mott“ two-spin-channel model of ferromagnets

“Dirac“ relativistic spin-orbit coupling

I

I I

I

Mott, 1936

Dirac, 1928

Two paradigms for spintronics

I

I I

I

Mott with ferromagnets

Dirac with ferromagnets Dirac with antiferromagnets

I I

I I

Mott with antiferromagnetsAntiferromagnetic MATERIALS playing ACTIVE role in spintronics

Fixed FMAFM

FM

FM

AFM

Ta/Ru/Ta

MnIr

MgO

Pt

NiFe

NiFe

Spin-valve with AFM electrode

Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Ta/Ru/Ta

MnIr

MgO

Pt

NiFe

NiFe

Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Spin-valve with AFM electrode

Ta/Ru/Ta

NiFe

MnIr

MgO

Pt

Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Spin-valve with AFM electrode

Ta/Ru/Ta

NiFe

MnIr

MgO

Pt

>100% spin-valve-like signal at ~50 mT

50

100

R [

k]

-1 0 1

B [ T ]

1.5 & 3nm IrMn

4K

Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Spin-valve with AFM electrode

Ta/Ru/Ta

NiFe

MnIr

MgO

Pt

Electrically measurable memory effect in AFM

-1000 -500 0 50020

40

60

80

R (

kohm

)Field (Oe)

Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Spin-valve with AFM electrode

Ta/Ru/Ta

NiFe

MnIrMgOPt

Small signal in control sample without IrMn -100 -50 0 5020

40

60

80

R (

kohm

)

Field (mT)

Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Spin-valve with AFM electrode

Scholl et al. PRL ‘04

See also Wang et al. PRL ’12: room-T AFM TAMR in CoPt/IrMn/AlOx/Pt

Spin-valve with AFM electrode

Writing by exchange-spring rotation of AFM by FM

B

[ o ]

50

100

R [k

]

-1 0 1B [ T ]

50

100

R [

k]

-1 0 1B [ T ]

-0.2 0 0.2Energy (eV)

50

-50

0

D

OS

/DO

S

spin-orbit coupling

AFM

Shick, TJ et al. PRB ’10see also Zemen, TJ et al. arXiv:1301.5369

Spin-valve with AFM electrode

-0.2 0 0.2Energy (eV)

50

-50

0

(DO

S00

1 –

DO

S11

0)/

DO

S

Shick, Wunderlich, TJ et al. PRB ‘10

IrMn, AuMn,...

Ferromagnets Antiferromagnets

Park, Wunderlich, Joo, Jung, Shin, TJ et al. PRL’08

Relativistic ab initio density-of-states anisotropy

Spin-valve with AFM electrode

Ta/Ru/Ta

MnIr

MgO

Pt

NiFe

Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13

AFM tunnel junction written by field-cool without FM

Ta/Ru/Ta

NiFe

MnIr

MgO

Pt

Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13

AFM tunnel junction written by field-cool without FM

MnIr

Pt

Field thermal-assisted MRAM

MgO

Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13

AFM tunnel junction written by field-cool without FM

Magnetic memory insensitive to magnetic fields & producing no stray fields

(RH-R

L)/

RL

(%)

MnIr

MgOPt

Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13

Bz

yx

AFM tunnel junction written by field-cool without FM

STT-MRAM

Spins injected from external polarizer in a non-uniform magnetic structure

Berger PRB ’96, Slonczewski JMMM ’96

MpM

Ie

Writing by current: non-relativistic spin-transfer torque

Spins injected from external polarizer in a non-uniform magnetic structure

I I

Mott with ferromagnets

I I

Mott with antiferromagnets

MpM

Ie

Berger PRB ’96, Slonczewski JMMM ’96

Writing by current: non-relativistic spin-transfer torque

M

Ie

Writing by current: relativistic spin-orbit torque

Manchon & Zhang, PRB ‘08, Chernyshev et al. Nature Phys.‘09, Miron et al. Nature Mater. ‘10, Fang, Ferguson, TJ et al. Nature Nanotech.‘11

Miron et al., Nature ‘11

Spin current in a uniform magnetic structure without external polarizer

In-plane current switching

Manchon & Zhang, PRB ‘08, Chernyshev et al. Nature Phys.‘09, Miron et al. Nature Mater. ‘10, Fang, Ferguson, TJ et al. Nature Nanotech.‘11

Spin current in a uniform magnetic structure without external polarizer

I I

Dirac with ferromagnets Dirac with antiferromagnets

I I

M

Ie Andrew Ferguson, W18.00007

Writing by current: relativistic spin-orbit torque

M

Spintronics & transistors Spintronics & photonics

Tc < room-T

Ohno, Dietl et al., Science ’98,’00, TJ et al., Rev. Mod. Phys. ‘06

Petr Němec, R18.00001

FM semiconductors

Writing by electric field or light: Magnetic semiconductor spintronics

II-VI FM TC (K) AFM TN (K)

MnO 122

MnS 152

MnSe 173

MnTe 323

EuO 67

EuS 16

EuSe 5

EuTe 10

II-V-IV-V FM TC (K) AFM TN (K)

MnSiN2 490

III-V FM TC (K) AFM TN (K)

FeN 100

FeP 115

FeAs 77

FeSb 100-220

GdN 72

GdP 15

GdAs 19

GdSb 27

I-VI-III-VI FM TC (K) AFM TN (K)

CuFeO2 11

CuFeS2 825

CuFeSe2 70

CuFeTe2 254

I-II-V FM TC (K) AFM TN (K)

Ia=Li, Na,..Ib=CuII=MnV=Sb,As, P

> room T

Semiconductors: more AFMs than FMs and high-TN AFMs

TJ, Novák, Martí et al. PRB ’11, Cava Viewpoint, Physics ’11, Máca, Mašek, TJ et al. JMMM ’12

Spin-orbit-coupled Mott AFM semiconductor

Kim et al., Science ’09, Jin et al. PRB ‘09, Arita et al. PRL ‘12

0 90 180 270 360-1

0

1

R

/R (

%)

0 90 180 270 360-1

0

1

0 90 180 270 360-1

0

1

R

/R (

%)

0 90 180 270 360-1

0

1

0 90 180 270 360-1

0

1

(°)

R

/R (

%)

0 90 180 270 360-1

0

1

(°)

LSMO

SIO Ag

Pt

LSMO

SIO AgAg

T = 200 KT = 200 K

T = 40 KT = 40 K

T = 4.2 K

T = 4.2 K

0 100 200 3000

1000

2000

3000

T (K)

R (

)

R13

R23

-20 0 20

-10

0

10

V (mV)

I (

A)

T = 4.2 K

Ohmic AMR in Sr2IrO4 AFM semiconductor

Xavier Martí, T18.00011

B.G. Park, J. Wunderlich, X. Marti, V. Holy, Y. Kurosaki, M. Yamada, H. Yamamoto, A. Nishide, J. Hayakawa, H. Takahashi, A.B. Shick, T. Jungwirth Nature Mater. 10 (2011) 347 – 351

X. Marti, B. G. Park, J. Wunderlich, H. Reichlova, Y. Kurosaki, M. Yamada, H. Yamamoto, A. Nishide, J. Hayakawa, H. Takahashi, T. Jungwirth Phys. Rev. Lett. 108 (2012) 017201(1) - 017201(4)

D. Petti, E. Albisetti, H. Reichlová, J. Gazquez, M. Varela, M. Molina-Ruiz, A. F. Lopeandía, K. Olejník, V. Novák, I. Fina, B. Dkhil, J. Hayakawa, X. Marti, J. Wunderlich, T. Jungwirth, R. Bertacco submitted to Appl. Phys. Lett.

Metal AFM spintronicsMetal AFM spintronics

Semiconductor AFM spintronicsSemiconductor AFM spintronics

T. Jungwirth, V. Novák, X. Marti, M. Cukr, F. Máca, A.B. Shick, J. Mašek, P. Horodyska, P. Němec, V. Holý, J. Zemek, P. Kužel, I. Němec, B. L. Gallagher, R. P. Campion, C. T. Foxon, J. Wunderlich Phys. Rev. B 83 (2011) 035321(1) - 035321(6).

C. Rayan Serrao, Jian Liu, J.T. Heron, G. Singh-Bhalla, A. Yadav, S.J. Suresha, R. J. Paull, D. Yi, J.-H. Chu, M. Trassin, A. Vishwanath, E. Arenholz, C. Frontera, J. Železný, J. Mašek, T. Jungwirth, X. Marti, R. Ramesh Phys. Rev. B 87 (2013) 085121(1)-08512(6)

P. Wadley, V. Novak, R. P. Campion, C. Rinaldi, X. Mart, H. Reichlova, J. Zelezny, J. Gazquez, M. A. Roldan, M. Varela, D. Khalyavin, S. Langridge, D. Kriegner,10 F. Maca, J. Masek, V. Holy, A. W. Rushforth, K. W. Edmonds, B. L. Gallagher, C. T. Foxon, J. Wunderlich, and T. Jungwirth, to be published

X. Marti, I. Fina, D. Yi, J. Liu, J.H. Chu, C. Rayan-Serrao, S. Suresha, J. Železný, T. Jungwirth, J. Fontcuberta, R. Ramesh, to be published