Transcript Part 2
Spintronics: How spin can act on charge carriers and vice versa Tomas Jungwirth Institute of Physics Prague University of Nottingham Mott without spin current Mott with spin current I Spintronics I From Wikipedia, the free encyclopedia Spintronics (a pormanteau meaning spin transport electronics).... GMR 1988 MRAM 2006 Dirac without current through magnet Dirac with current through magnet I AMR 1857 I HD Read-heads 1990‘s Writing by current: non-relativistic spin-transfer torque Spins injected from external polarizer in a non-uniform magnetic structure Mp M Ie Berger PRB ’96, Slonczewski JMMM ’96 STT-MRAM Writing by current: non-relativistic spin-transfer torque Spins injected from external polarizer in a non-uniform magnetic structure Mp M Ie Berger PRB ’96, Slonczewski JMMM ’96 Mott I I Writing by current: relativistic spin-orbit torque Spin current in a uniform magnetic structure with broken space-inversion symmetry M Ie Manchon & Zhang, PRB ‘08, Chernyshev et al. Nature Phys.‘09, Miron et al. Nature Mater. ‘10, Fang, Ferguson, TJ et al. Nature Nanotech.‘11 Zinc-blende (Ga,Mn)As: broken bulk inversion symmetry In-plane current switching Miron et al., Nature ‘11 Co/Pt: broken structural inversion symmetry Writing by current: relativistic spin-orbit torque Spin current in a uniform magnetic structure with broken space-inversion symmetry M Ie Manchon & Zhang, PRB ‘08, Chernyshev et al. Nature Phys.‘09, Miron et al. Nature Mater. ‘10, Fang, Ferguson, TJ et al. Nature Nanotech.‘11 Dirac Zinc-blende (Ga,Mn)As: broken bulk inversion symmetry I I Materials Paramagnets: very frequent Disordered M=0: bad for direct manipulation by magnetic field, no magnetic memory compatible with semiconductors: transitsors & photonics Spin Hall effect Kato et al., Science ’04, Wunderlich, TJ et al. Phys. Rev. Lett. ’05 Spin-orbit Magnetic field of moving nucleus in electron‘s rest frame Paramagnets: very frequent Disordered M=0: bad for direct manipulation by magnetic field, no magnetic memory compatible with semiconductors: transitsors & photonics Spin Hall effect Spin-orbit Magnetic field of moving nucleus in electron‘s rest frame Paramagnets: very frequent Disordered M=0: bad for directmanipulation by magnetic field, no magnetic memory compatible with semiconductors: transitsors & photonics Spin-orbit Antiferromagnets: frequent Magnetic field of moving nucleus in electron‘s rest frame Ordered M=0: bad for direct manipulation by magnetic field, good for retention with magnetic field around compatible with semiconductors: transitsors & photonics Ferromagnets: rare Eexchange Ordered M0: good for direct manipulation by magnetic field, bad for retention with magnetic field around not well compatible with semiconductors Egap EFermi Magnetic-field control of FMs: scales with current Control by current via spin torques: scales with current density Control by photo-carriers via spin torques: sub ps timescales 0.1 pJ Relativistic spin-orbit torques might work equally well in AFMs plus photocarriers in SCs Electro-static field control via relativistic magnetic anisotropy effects: 1fJ Should work equally well or better in AFMs: more choices including SCs (or piezo-electric) Mott with antiferromagnets Mott with ferromagnets I I I Dirac with ferromagnets I I Dirac with antiferromagnets I I I Spintronics with antiferromagnets AFM IrMn Dirac I I FM AFM 2 AMR ~ (m) Shick, Wunderlich, TJ, et al., PRB‘10 Spin-valve with AFM electrode Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Pt NiFe MgO NiFe MnIr Ta/Ru/Ta Spin-valve with AFM electrode Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Pt MgO NiFe MnIr Ta/Ru/Ta NiFe Spin-valve with AFM electrode Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Pt MgO MnIr NiFe Ta/Ru/Ta Spin-valve with AFM electrode Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 100 1.5 & 3nm IrMn R [k] Pt MgO MnIr 50 NiFe Ta/Ru/Ta -1 4K 0 B[T] 1 >100% spin-valve-like signal at ~50 mT Spin-valve with AFM electrode Pt MgO MnIr R (kohm) Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 80 60 40 NiFe Ta/Ru/Ta 20 -1000 -500 0 Field (Oe) 500 Electrically measurable memory effect in AFM Spin-valve with AFM electrode Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Pt MgO MnIr NiFe R (kohm) Ta/Ru/Ta 80 60 40 20 -100 -50 0 Field (mT) 50 Small signal in control sample without IrMn Spin-valve with AFM electrode I Park, Marti, Wunderlich,TJ et al. Nature Mat. ’11, PRL ’12 Writing by magnetic field via FM/AFM exchange-spring I B ~100% AFM-TAMR AFM memory effect 50 -1 [o] R (k) R [k] 100 0 B[T] 1 80 60 40 20 -100 Wang et al. PRL ’12: room-T AFM TAMR in CoPt/IrMn/AlOx/Pt -50 0 B [mT] 50 AFM tunnel junction written by field-cool without FM Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13 Pt MgO MnIr NiFe Ta/Ru/Ta AFM tunnel junction written by field-cool without FM Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13 Pt MgO MnIr NiFe Ta/Ru/Ta AFM tunnel junction written by field-cool without FM Petti, Marti, Bertacco, TJ et al., submitted to APL ‘13 Pt MgO MnIr Ta/Ru/Ta Compare: thermal-assisted MRAM AFM tunnel junction written by field-cool without FM I Petti, Marti, Bertacco, TJ et al., APL ‘13 Principle: increase susceptibility write by field back to negligible susceptibility AFM I z Pt MgO B x y MnIr (RH-RL)/RL (%) Ta/Ru/Ta Magnetic memory insensitive to magnetic fields & producing no stray fields Control by electro-static fields or photo-carriers: magnetic semiconductors Spintronics & transistors Spintronics & photonics M Tc < room-T Ohno, Dietl et al., Science ’98,’00, TJ et al., Rev. Mod. Phys. ‘06 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 AFM TN (K) III-V MnO 122 FeN 100 MnS 152 FeP 115 MnSe 173 FeAs 77 MnTe 323 FeSb 100-220 II-VI FM TC (K) FM TC (K) AFM TN (K) EuO 67 GdN 72 EuS 16 GdP 15 EuSe 5 GdAs 19 EuTe 10 GdSb 27 AFM TN (K) II-V-IV-V CuFeO2 11 MnSiN2 CuFeS2 825 I-II-V CuFeSe2 70 CuFeTe2 254 Ia=Li, Na,.. Ib=Cu II=Mn V=Sb,As, P I-VI-III-VI FM TC (K) FM TC (K) AFM TN (K) 490 FM TC (K) AFM TN (K) > room T Spin-orbit-coupled Mott AFM semiconductor I I Kim et al., Science ’09, two focused sessions at APS MM 2013 Ohmic AMR in Sr2IrO4 AFM semiconductor I Writing by magnetic field via FM/AFM exchange-spring I B 3000 R13 R23 10 I (A) R () 2000 1000 T = 4.2 K 0 Martí, TJ, Fontcuberta, Ramesh, et al. preprint -10 -20 0 0 0 V (mV) 100 200 T (K) 20 300 Ohmic AMR in Sr2IrO4 AFM semiconductor Pt SIO Ag Ag LSMO R/R (%) 1 T = 200 K 0 -1 0 0 90 180 270 360 R/R (%) 1 -1 0 90 180 270 360 0 90 180 270 360 0 90 180 270 360 (°) 1 T = 40 K 0 -1 0 0 90 180 270 360 1 R/R (%) Ag LSMO 1 Martí, TJ, Fontcuberta, Ramesh, et al. preprint SIO -1 1 T = 4.2 K 0 -1 0 0 90 180 270 360 (°) -1