Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 63: III-V Semiconductors
HL 63.3: Vortrag
Freitag, 26. März 2010, 10:45–11:00, H13
Damping processes on coherent zero field spin oscillations in high mobility, two-dimensional electron systems — •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 present time-resolved studies of two-dimensional electron systems with high mobility, where at low temperatures the weak-scattering regime of the D’yakonov-Perel spin relaxation mechanism is accessible. Using the all-optical time-resolved Faraday rotation technique, coherent oscillations of the optically-excited spin ensemble about the intrinsic spin-orbit field are observable. The lifetimes of these oscillations are limited by scattering mechanisms, which change the electrons k vector or an anisotropy of the k-dependent effective spin-orbit field. By investigating samples with different mobilities of 1.5 million cm2/Vs and 15 million cm2/Vs, temperature dependent measurements showed that in the lower mobility sample the momentum scattering time τp limits the lifetime of the zero field oscillations, whereas in the sample with the ultra high mobility the limiting processes are electron-electron scattering events. Lowering the excitation density led to a lower temperature of the electron system and due to increasing e-e-scattering times to an increasing lifetime of the observed spin beats.