Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 35: Spin controlled transport II
HL 35.12: Vortrag
Mittwoch, 27. Februar 2008, 17:15–17:30, ER 164
Efficient optical spin detection in the absence of magnetic fields at room temperature — •Stephan Hövel1, Nils C. Gerhardt1, Martin R. Hofmann1, Fang-Yuh Lo2, Dirk Reuter2, Andreas D. Wieck2, Ellen Schuster3, and Werner Keune3 — 1AG Optoelektronische Bauelemente und Werkstoffe, Ruhr-University Bochum, Germany — 2Lehrstuhl für angewandte Festkörperphysik, Ruhr-University Bochum, Germany — 3Laboratorium für Angewandte Physik, University Duisburg-Essen, Germany
GaAs/AlGaAs-diodes have been used in a Faraday-geometry to transfer a circular optical excitation into a spin current at room temperature. The optical information is transferred into a current density which is dependent on the magnetization of the deposited Fe/MgO/n-AlGaAs-tunneling barrier. Detection is possible for a remanent state of magnetization and the current shows a strong proportionality to the circular state of polarization irradiating the diode. Furthermore, the current signal reproduces the remanent behaviour of the Fe. A comparison with a pure Schottky tunnel contact at a Fe/n-AlGaAs-interface diode shows strong current fluctuations for the latter which indicates a worse interface quality than for the case of an oxide-barrier. Few percent of polarization degree difference are measureable without significant temperature dependence up to room temperature and the sensitivity even rises for higher excitation intensities. This work has been supported by the DFG within the SFB491.