Spintronics: How spin can act on charge carriers and vice versa Tomas Jungwirth University of...

Spintronics: How spin can act on charge carriers and vice versa

Tomas Jungwirth

University of Nottingham

Institute of Physics Prague

Mott with spin current

Dirac with current through magnet

Mott without spin current

Spintronics

From Wikipedia, the free encyclopedia

Spintronics (a pormanteau meaning spin transport electronics)....

Dirac without current through magnet

I I

I I

I I

MRAM2006

GMR1988

AMR1857

HD Read-heads1990‘s

STT-MRAM

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

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

I I

Mott

MpM

Ie

Berger PRB ’96, Slonczewski JMMM ’96

Writing by current: non-relativistic spin-transfer torque

M

Ie

Miron et al., Nature ‘11

Spin current in a uniform magnetic structure with broken space-inversion symmetry

In-plane current switchingZinc-blende (Ga,Mn)As: broken bulk inversion symmetry

Co/Pt: broken structural inversion symmetry

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

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

I I

Dirac

M

Ie

Writing by current: relativistic spin-orbit torque

Spin current in a uniform magnetic structure with broken space-inversion symmetry

Zinc-blende (Ga,Mn)As: broken bulk inversion symmetry

Materials

Disordered M=0: bad for direct manipulation by magnetic field, no magnetic memory compatible with semiconductors: transitsors & photonics

Paramagnets: very frequent

Magnetic field of moving nucleusin electron‘s rest frame

Spin-orbit

Kato et al., Science ’04, Wunderlich, TJ et al. Phys. Rev. Lett. ’05

Spin Hall effect

Disordered M=0: bad for direct manipulation by magnetic field, no magnetic memory compatible with semiconductors: transitsors & photonics



Spin-orbitSpin Hall effect

Ordered M0: good for direct manipulation by magnetic field, bad for retention with magnetic field around not well compatible with semiconductors

Ferromagnets: rare

Disordered M=0: bad for directmanipulation by magnetic field, no magnetic memory compatible with semiconductors: transitsors & photonics



Spin-orbitAntiferromagnets: frequent

Ordered M=0: bad for direct manipulation by magnetic field, good for retention with magnetic field around compatible with semiconductors: transitsors & photonics

Egap

Eexchange

EFermi

Magnetic-field control of FMs:scales with current

Control by currentvia spin torques:scales with current density

0.1 pJ

Electro-static field control via relativisticmagnetic anisotropy effects:1fJ

(or piezo-electric)

Should work equally well or better in AFMs: more choices including SCs

Control by photo-carriers via spin torques:sub ps timescales

Relativistic spin-orbit torques might work equally well in AFMs plus photocarriers in SCs

Laser

I

I I

I

Mott with ferromagnets

Dirac with ferromagnets Dirac with antiferromagnets

I I

I I

Mott with antiferromagnets

FM AFM

Shick, Wunderlich, TJ, et al., PRB‘10

Spintronics with antiferromagnets

AFM IrMn

2)(~ mAMR

I I

Dirac

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



Ta/Ru/Ta

NiFe

MnIr

MgO

Pt



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



Ta/Ru/Ta

NiFe

MnIr

MgO

Pt

Electrically measurable memory effect in AFM

-1000 -500 0 50020

40

60

80

R (

kohm

)Field (Oe)



Ta/Ru/Ta

NiFe

MnIrMgOPt

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

40

60

80

R (

kohm

)

Field (mT)



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

Writing by magnetic field via FM/AFM exchange-spring

B

[ o ]

50

100

R [k

]

-1 0 1B [ T ]

I

I

-100 -50 0 5020

40

60

80

R (

k)

B [mT]

~100% AFM-TAMR AFM memory effect



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



Ta/Ru/Ta

MnIr

Pt

Compare: thermal-assisted MRAM

MgO



Principle: increase susceptibility write by field back to negligible susceptibility AFM

I

I

Magnetic memory insensitive to magnetic fields & producing no stray fields

(RH-R

L)/

RL

(%)

Ta/Ru/Ta

MnIr

MgOPt

Bz

yx

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


M

Spintronics & transistors Spintronics & photonics

Control by electro-static fields or photo-carriers: magnetic semiconductors

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

Tc < room-T

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

Magnetic 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, two focused sessions at APS MM 2013

I

I

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 semiconductorI

I

B

Writing by magnetic field via FM/AFM exchange-spring

Martí, TJ, Fontcuberta, Ramesh, et al. preprint

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 K

T = 40 K

T = 4.2 K

Ohmic AMR in Sr2IrO4 AFM semiconductor

Martí, TJ, Fontcuberta, Ramesh, et al. preprint

Spintronics: How spin can act on charge carriers and vice versa Tomas Jungwirth University of...

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