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 II II MRAM 2006 GMR 1988 AMR 1857 HD Read-heads 1990‘s

STT-MRAM Berger PRB ’96, Slonczewski JMMM ’96 MpMp M IeIe Writing by current: non-relativistic spin-transfer torque Spins injected from external polarizer in a non-uniform magnetic structure

II Mott MpMp M IeIe Berger PRB ’96, Slonczewski JMMM ’96 Writing by current: non-relativistic spin-transfer torque

M IeIe Miron et al., Nature ‘11 Spin current in a uniform magnetic structure with broken space-inversion symmetry In-plane current switching Zinc-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 IeIe 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 nucleus in 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 Paramagnets: very frequent Magnetic field of moving nucleus in electron‘s rest frame Spin-orbit Spin Hall effect

Ordered M  0: 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 Paramagnets: very frequent Magnetic field of moving nucleus in electron‘s rest frame Spin-orbit Antiferromagnets: frequent Ordered M=0: bad for direct manipulation by magnetic field, good for retention with magnetic field around compatible with semiconductors: transitsors & photonics E gap E exchange E Fermi

Magnetic-field control of FMs: scales with current Control by current via spin torques: scales with current density 0.1 pJ Electro-static field control via relativistic magnetic 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 II II Mott with antiferromagnets 

FMAFM Shick, Wunderlich, TJ, et al., PRB‘10 Spintronics with antiferromagnets AFM IrMn II Dirac

Ta/Ru/Ta MnIr MgO Pt NiFe Spin-valve with AFM electrode Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12

Ta/Ru/Ta MnIr MgO Pt 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 R [k  ] 01 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 Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Spin-valve with AFM electrode

Ta/Ru/Ta NiFe MnIr MgO Pt Small signal in control sample without IrMn Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Spin-valve with AFM electrode

Wang et al. PRL ’12: room-T AFM TAMR in CoPt/IrMn/AlO x /Pt Writing by magnetic field via FM/AFM exchange-spring B  [ o ] R [k  ] 01 B [ T ] II ~100% AFM-TAMRAFM memory effect Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 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

Ta/Ru/Ta MnIr Pt Compare: thermal-assisted MRAM MgO Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13 AFM tunnel junction written by field-cool without FM

Principle: increase susceptibility  write by field  back to negligible susceptibility AFM II Magnetic memory insensitive to magnetic fields & producing no stray fields (R H -R L )/R L (%) Ta/Ru/Ta MnIr MgO Pt B z y x Petti, Marti, Bertacco, TJ et al., APL ‘13 AFM tunnel junction written by field-cool without FM

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 T c < room-T

II-VIFM T C (K)AFM T N (K) MnO122 MnS152 MnSe173 MnTe323 EuO67 EuS16 EuSe5 EuTe10 II-V-IV-VFM T C (K)AFM T N (K) MnSiN III-VFM T C (K)AFM T N (K) FeN100 FeP115 FeAs77 FeSb GdN72 GdP15 GdAs19 GdSb27 I-VI-III-VIFM T C (K)AFM T N (K) CuFeO 2 11 CuFeS CuFeSe 2 70 CuFeTe I-II-VFM T C (K)AFM T N (K) Ia=Li, Na,.. Ib=Cu II=Mn V=Sb,As, P > room T Magnetic semiconductors: more AFMs than FMs and high-T N 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 II

Ohmic AMR in Sr 2 IrO 4 AFM semiconductor II B Writing by magnetic field via FM/AFM exchange-spring Martí, TJ, Fontcuberta, Ramesh, et al. preprint

LSMO SIO Ag Pt LSMO SIO Ag T = 200 K T = 40 K T = 4.2 K Ohmic AMR in Sr 2 IrO 4 AFM semiconductor Martí, TJ, Fontcuberta, Ramesh, et al. preprint