Semiconductor spintronics Semiconductor spintronics Tomáš Jungwirth University of Nottingham Bryan Gallagher, Tom Foxon, Richard Campion, et al. Hitachi Cambridge Jorg Wunderlich, David Williams, et al. Institute of Physics ASCR, Prague a Shick, Jan Mašek, Vít Novák, Kamil Olejník n Kučera, Karel Výborný, Jan Zemen, et al. University of Texas Texas A&M Univ. Allan MacDonald, Qian Niu et al. Jairo Sinova, et al. NERC SWAN
NERC SWAN. Semiconductor spintronics. Tom áš Jungwirth. Universit y of Nottingham Bryan Gallagher, Tom Foxon, Richard Campion, et al. Institute of Physics ASCR, Prague Sasha Shick , Jan Ma šek, Vít Novák, Kamil Olejník Jan Kučera, Karel Výborný, Jan Zemen, et al. - PowerPoint PPT Presentation
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total wf antisymmetric = orbital wf antisymmetric * spin wf symmetric (aligned)
FEROFERO MAGMAG NETNET
ee--
• RobustRobust (can be as strong as bonding in solids)(can be as strong as bonding in solids)
• Strong coupling to magnetic fieldStrong coupling to magnetic field (weak fields = anisotropy fields needed (weak fields = anisotropy fields needed only to reorient macroscopic moment)only to reorient macroscopic moment)
many-body
ee--
relativistic single-particle
effSO BsH
p)V(cm2
1B
22eff
V
BBeffeff
pss
Spin-orbit couplingSpin-orbit coupling (Dirac eq. in external field V(r) & 2nd-order in v /c around non-relativistic limit)
• Current sensitive to magnetizationCurrent sensitive to magnetization directiondirection
1.1. Basic Basic physical principles of the operation of spintronic devicesphysical principles of the operation of spintronic devices
2.2. Current metal Current metal sspipintronics in HDD read-heads and memory chipsntronics in HDD read-heads and memory chips
3.3. Research in semiconductor Research in semiconductor sspintronipintronics cs
4. Summary4. Summary
Current spintronics applications Current spintronics applications
First hard discFirst hard disc (1956) (1956) - - classical electromagnet for read-outclassical electromagnet for read-out
From PC hard drives ('90)From PC hard drives ('90)to mto miicro-discscro-discs - - spintronispintronic read-headsc read-heads
MBMB’s’s
10’s-100’s 10’s-100’s GBGB’s’s
1 bit: 1mm x 1mm1 bit: 1mm x 1mm
1 bit: 101 bit: 10-3-3mm x 10mm x 10-3-3mmmm
Anisotropic magnetoresistance (AMR) read headAnisotropic magnetoresistance (AMR) read head1992 - dawn of spintronics1992 - dawn of spintronics