Regensburg 2016 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 14: Spintronics: Transport and Theory
HL 14.8: Talk
Monday, March 7, 2016, 17:00–17:15, H13
Enabling spin-to-charge conversion in semiconductor spintronics through time-reversal and structure-inversion asymmetry: Fe on Ge(111) — •Ashis K. Nandy1, Nguyen H. Long1, Simon Oyarzun2, Jean-Marie George3, Henri Jaffres3, Stefan Blügel1, and Matthieu Jamet2 — 1Peter Grünberg Institute and Institute for Advanced Simulation, FZJ & JARA, D-52425 Jülich, Germany — 2Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France — 3Univ. Paris-Sud, F-91405 Orsay, France
One important goal of semiconductor spintronics is the realisation of the Si based spin-field-effect transistor. Its realisation is challenged by the small spin-Hall effect in bulk Si and Ge. Using first-principles theory based on DFT we show that the surface of Ge(111) introduces a large snowflake-like Rashba effect with a locking of momentum vector k to mostly out-of-plane spin components, whose energy dispersion shows a k3-dependence in the vicinity of Γ. Breaking the time-inversion symmetry by depositing Fe films on Ge(111) we exhibit a strong hybridization of Fe-d with Ge-p states, leading to a spin-splitting of the Ge Rashba states, where the majority snowflake-like Rashba states are occupied. The joint effect of exchange and Rashba spin-orbit interaction leads to an electronic structure with a lack of mirror symmetry in the plane normal to the surface and in the direction of the in-plane magnetization. Considering the asymmetry of the Fermi surface and the k3-dependence of part of the electronic structure, we present arguments supporting experimentally observed large charge currents when generated by intrinsic spin-pumping in the interfacial electron gas.