Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 91: Poster Session: Spintronics / Magnetic Semiconductors / Transport
HL 91.7: Poster
Donnerstag, 29. März 2012, 16:00–19:00, Poster D
Spin dynamics and anomalous spin diffusion in high-mobility (110) GaAs-based quantum wells — •R. Völkl1, T. Korn1, S.A. Tarasenko2, M. Griesbeck1, M. Schwemmer1, D. Schuh1, W. Wegscheider3, and C. Schüller1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany — 2A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia — 3ETH Zurich, Switzerland
Here, we present a study of electron spin dynamics in symmetrical, high mobility (110)-grown, GaAs-based quantum wells, focusing on spin lifetimes and the motion of spin-polarized electrons in the sample, as well as creating spin polarization due to a nonzero electron drift velocity. The Hanle-MOKE method is used to determine the spin lifetime and for mapping the motion of spin-polarized electrons. Spin lifetimes up to 54 ns are found for weak optical pumping, for stronger pumping the lifetime decreases rapidly. High excitation intensity entails an ascent of the hole-density, which leads to a faster decay of electron spin via the Bir-Aronov-Pikus mechanism, as well as to more recombination. Spin diffusion is studied by moving the pump beam using a motorized mirror. A maximum of the net spin polarization is observed a few microns away from the pump spot, due to a reduced influence of photo generated holes. An applied electric field yields a nonzero electron drift velocity. Due to the spatial dependence of the Dresselhaus field, an out-of-plane spin polarization is observed while an electric current runs along [1-10] direction. Financial support by the DFG via SFB 689 and SPP 1285 is gratefully acknowledged