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Published bySullivan Morphew Modified over 10 years ago
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Spintronics: How spin can act on charge carriers and vice versa
Tomas Jungwirth University of Nottingham Institute of Physics Prague
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Reading by GMR (TMR) Writing by STT STT-MRAM
Fert, Grünberg, et al. 1988 Nobel Prize 2007 Sloncyewski, Berger, 1996 Buckley Prize at APS MM 2013
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Read-out: non-relativistic giant magnetoresistance (GMR)
Ie Ie Fert, Grünberg, et al. 1988 Nobel Prize 2007
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Read-out: non-relativistic giant magnetoresistance (GMR)
Fert, Grünberg, et al. 1988 Nobel Prize 2007 Antiferromagnetic arrangement of a ferromagnetic multilayer at B=0
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Writing information in spin-valve: towards spintronic memory (MRAM)
1. AFM coupling between FMs at B=0 FM FM FM 2. One FM flips harder than the other FM Soft FM Hard FM Soft FM Hard FM 3. One FM pinned by AFM material Fixed FM AFM Soft FM Fixed FM AFM Soft FM
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Towards reliable switching of a particular MRAM bit
Fixed FM NM AFM Soft FM
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Toggle switching first commercial MRAMs
FM “Synthetic AFM“ FM Fixed FM AFM
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Writing by current: non-relativistic spin-transfer torque (STT)
Spins injected from external polarizer in a non-uniform magnetic structure Mp M Ie Sloncyewski, Berger, 1996 Buckley Prize at APS MM 2013
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MRAM: universal memory
Write with magnetic field: on market since 2006 scales with current Write with current (STT-MRAM): on market since 2013 scales with current density
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MRAM: universal memory
Compatible with CMOS GB MRAMs in few years
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Conventional architecture with CMOS New architectuture with MRAM
kB MB GB huge gap TB
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Worldwide MRAM development
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Spin-transistor Datta, Das, APL 1990
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Conventional architecture with CMOS
New architectuture with spin-memory/logic
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Read-out: non-relativistic giant magnetoresistance (GMR)
Ie Ie Fert, Grünberg, et al. 1988 Nobel Prize 2007
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Read-out: relativistic anisotropic magnetoresistance (AMR)
Spintronic effect 150 years ahead of time M Ie Kelvin, 1857
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Read-out: relativistic anisotropic magnetoresistance (AMR)
Spintronic effect 150 years ahead of time M Ie Kelvin, 1857
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Two paradigms for spintronics
“Mott“ non-relativistic two-spin-channel model of ferromagnets I I Mott, 1936 “Dirac“ relativistic spin-orbit coupling I I Dirac, 1928
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2 2 Spin-orbit coupling nucleus rest frame electron rest frame
Lorentz transformation Thomas precession
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Spin-orbit coupling: quantum relativistic physics
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Spin-orbit coupling: quantum relativistic physics
Dirac equation
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Spin-orbit coupling: quantum relativistic physics
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Ultra-relativistic quantum particles (neutrino) Dirac equation
spin and orbital motion coupled
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Ultra-relativistic quantum particles (neutrino) Dirac equation
spin and orbital motion coupled
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Ultra-relativistic quantum particles (neutrino) Dirac equation
spin and orbital motion coupled
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Ohmic “Dirac“ device: AMR
Kelvin, 1857 Magnetization-orientation-dependent scattering
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Ohmic “Mott“ device: GMR
Fert, Grünberg, 1988 Spin-channel-dependent scattering
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Tunneling “Mott“ device: TMR
Julliere 1975, Moodera et al., Miyazaki & Tezuka 1995 MRAM Spin-channel-dependent tunneling DOS
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Tunneling “Dirac“ device: TAMR
Gould, TJ et al. PRL ‘04 Magnetization-orientation-dependent tunneling DOS
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Magnetization-orientation-dependent chemical potential
Chemical potential controlled “Dirac“ device Wunderlich, TJ et al. PRL ‘06
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Magnet Dielectric M Non-magnetic channel I I
Dirac spintronic device without current through magnet I I Chemical potential of magnetic gate changes Charge on magnetic gate changes Polarisation charge on non-magnetic channel Magnet - + Dielectric - + M Non-magnetic channel Ciccarelli, Ferguson, TJ et al. APL ‘12
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Magnet Dielectric M Non-magnetic channel I I
Dirac spintronic device without current through magnet I I Chemical potential of magnetic gate changes Charge on magnetic gate changes Polarisation charge on non-magnetic channel Magnet - + Dielectric - + M Non-magnetic channel Ciccarelli, Ferguson, TJ et al. APL ‘12
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Magnet Dielectric M Non-magnetic channel I I
Dirac spintronic device without current through magnet I I Chemical potential of magnetic gate changes Charge on magnetic gate changes Polarisation charge on non-magnetic channel Magnet - + Dielectric - + M - + Non-magnetic channel - + - + Ciccarelli, Ferguson, TJ et al. APL ‘12
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DVg = Dm/e Dirac spintronic device without current through magnet
Ciccarelli, Ferguson, TJ et al. APL ‘12
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Direct approach to spin-transistor
Inverted approach to spin-transistor
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Direct approach to spin-transistor
Inverted approach to spin-transistor
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Direct approach to spin-transistor
Inverted approach to spin-transistor
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Direct approach to spin-transistor
Inverted approach to spin-transistor
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Direct approach to spin-transistor
Inverted approach to spin-transistor
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