Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 3: III-V-Compounds: GaAs and related Materials
HL 3.1: Vortrag
Montag, 14. März 2011, 10:15–10:30, POT 151
Dynamic nuclear polarization in n-GaAs - free versus localized electrons — •Jie Huang1, Yuansen Chen1, A. Ludwig2, D Reuter2, A. D. Wieck2, and Gerd Bacher1 — 1Werkstoffe der Elektrotechnik and CeNIDE, Universität Duisburg-Essen, Bismarckstr. 81, D-47057 Duisburg, Germany — 2Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstr. 150,D-44780 Bochum, Germany
In spin dependent information processing using III-V semiconductors, the large electron-nuclear coupling plays an important role, e.g. in affecting the electron spin coherence through the hyperfine interaction. In our experiment, optically injected spin-polarized electrons are used to generate a dynamic nuclear polarization (DNP) in bulk n-GaAs. This results in a tiny variation of the electron Larmor precession frequency, which is probed by time resolved Kerr rotation. A saturated Overhauser field on the order of several 10 mT is obtained, depending on the helicity of the pump beam. Our experimental data indicate a significant difference of the DNP time constant for localized and itinerant electrons. This is explained by considering a model involving Fermi contact hyperfine interaction, spin exchange between donor electrons and itinerant electrons and nuclear spin diffusion.