Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.12: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Carrier spin dynamics in GaAs/AlGaAs quantum wells, studied by time-resolved Kerr rotation — •Liudmila Fokina¹, Vladimir Petrov³, Dmitri Yakovlev^1,2, and Manfred Bayer¹ — ¹Experimental Physics 2,Technical University Dortmund, 44221 Dortmund, Germany — ²A.F. Ioffe Physico-Technical Institute, 194017 St. Petersburg, Russia — ³Saint-Petersburg State University, 198504 Saint-Petersburg, Russia

In recent years, electron-spin orientation in semiconductors is considered as a promising way of realization of quantum information processing in solid-state systems. Therefore, the problem of lifetime and relaxation mechanisms of spin coherence in real systems becomes highly topical. We study experimentally electron spin coherence in GaAs/AlGaAs quantum wells with a low-dense as well as with high dense two-dimensional electron gas by means of pump-probe time-resolved Kerr rotation technique. To explore spin relaxation mechanisms, we have performed a systematic study of the spin dephasing time as a function of temperature, magnetic field and electron concentration. Electron spin beats have been measured in magnetic field up to 10 T, which allows to determine the transverse component of the electron g-factor. In case when the spin dephasing times becomes longer than several ns, we used the technique of the resonant spin amplification (RSA), which has been developed to extract spin lifetimes that exceed the pulse repetition interval of 13.2 ns. Finally we describe an unusual behaviour of the RSA signal in vicinity of zero magnetic field, which is caused by interaction of the electron spins with the nuclei.