Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 70: Spintronics: Mobile electrons and holes (with MA/TT)
HL 70.5: Vortrag
Donnerstag, 19. März 2015, 11:00–11:15, ER 164
Time and space resolved visualization of spin diffusion and drift in GaAs based two-dimensional electron gases — •Markus Schwemmer1, Roland Völkl1, Tobias Korn1, Sergey Tarasenko2, Dieter Schuh1, Dominique Bougeard1, Mariusz Ciorga1, Werner Wegscheider3, and Christian Schüller1 — 1Institute of Experimental and Applied Physics, Faculty of Physics, University of Regensburg, Germany — 2A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia — 3ETH Zurich, Switzerland
The combination of a femtosecond pulsed TiSa-Laser system with a magneto-optical Kerr effect microscope setup allows us to study time and space resolved propagation of an optically injected electron spin packet in a resident two-dimensional electron gas based on a modulation-doped AlGaAs/GaAs quantum well. The interplay between the Dresselhaus and Rashba fields according to crystallographic orientation and layer structure of the sample determines the electron spin dynamics. On one hand we present diffusive and current-driven motion of a spin packet in a sample in which the orientation of the optically injected spins point along the effective spin orbit field. Therefore D'yakonov-Perel spin dephasing is suppresed and a long spin coherence time can be attained. On the other hand the diffusive spreading of the initial spin packet in a sample with a spin-orbit interaction close to the spin helix regime is monitored, whereby a direct visualization of the helix pattern is achieved. Financial support by the DFG via SFB 689 and SPP 1285 is gratefully acknowledged.