Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: Spin controlled transport II

HL 35.4: Talk

Wednesday, February 27, 2008, 15:00–15:15, ER 164

Microscopic theory of intrinsic spin-Hall effect in semiconductor nanodevices — •Tillmann Kubis and Peter Vogl — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching

We have calculated spin-orbit induced spin polarizations in confined mesoscopic systems at low temperatures and in the presence of external magnetic fields. To this end, we have implemented the spin-dependent non-equilibrium Green's function method (NEGF) in open nanometer quantum systems and take into account the coupling of non-equilibrium spin occupancies and spin-resolved electronic scattering states. We have employed both the conventional continuum approximation of the spin-orbit interaction in the envelope function approximation as well as a microscopic relativistic tight-binding approach. The latter ensures the spin-orbit effects are properly taken into account for any degree of charge confinement and localization and to all orders in the electron wave vector. While the quantitative results differ, we show that both methods yield the same qualitative trends in the calculated spin polarization, its dependence on confinement, on the spin-orbit interaction strength and on the charge density. In addition, we show that very significant spin polarizations near spin-neutral contacts can be generated in 3-terminal devices without any external magnetic fields. These devices appear to be promising candidates for efficient semiconductor based spin-polarizers.