Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 60: Poster II: Optical Properties, incl. Photonic Crystals and Ultrafast Phenomena
HL 60.39: Poster
Thursday, March 25, 2010, 18:00–20:00, Poster D1
Cyclotron effect on coherent spin precession of two-dimensional electrons — •Michael Griesbeck1, Mikhail Glazov2, Tobias Korn1, Dominik Waller1, Dieter Schuh1, Werner Wegscheider1, and Christian Schüller1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040 Regensburg, Germany — 2A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Peterburg, Russia
We report on time-resolved studies of a two-dimensional electron system (2DES) with a very high mobility of about 15 million cm2/Vs at sub-Kelvin temperatures. Using the all-optical time-resolved Faraday rotation technique, we could observe coherent oscillations of the optically excited electron spin ensemble about the intrinsic spin-orbit field. By applying classical magnetic fields normal to the sample plane, we were able to detect at sub-Kelvin temperatures the predicted fast oscillations of the spin ensemble about a non-zero value and a strong increase of the spin dephasing time. The fast oscillations rise due to an interplay of the ballistic cyclotron motion of the electrons and the precession of the electrons spins about the intrinsic spin-orbit field. The cyclotron motion rotates the k-dependent spin-orbit fields in the sample plane, this leads to the fast oscillations with a frequency determined by the geometric sum of the cyclotron frequency and the spin-orbit field. The determined values for the oscillation frequency, the oscillation amplitude and the spin dephasing times of the long living tail are in good agreement with a theory based on a kinetic equation approach.