Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 34: Spin controlled transport II
HL 34.10: Vortrag
Mittwoch, 25. März 2009, 16:45–17:00, BEY 118
Spatial Imaging of Spins Optically Excited by Linearly Polarized Light — •Stefan Göbbels1,2, Paul Schlammes1,2, Christian Rodenbücher1,2, Markus Hagedorn1,2, Klaus Schmalbuch1,2, Gernot Güntherodt1,2, Thomas Schäpers3,2, Mikhail Lepsa3,2, and Bernd Beschoten1,2 — 1II. Physikalisches Institut, RWTH Aachen, Templergraben 55, 52056 Aachen — 2Jülich-Aachen Research Alliance, JARA - Fundamentals of Future Information Technology — 3Institut für Bio- und Nanosysteme IBN-1, Forschungszentrum Jülich, 52425 Jülich
Optical orientation is a well established technique to optically excite electron spins in semiconductors. In conventional all-optical pump-probe experiments a circularly polarized pump beam is used to generate spin-polarized electrons by transferring angular momentum from the photons to the electrons. -- We present a new method for optical spin orientation using a linearly polarized pump beam. The polarization mechanism is studied by all-optical time-resolved Faraday microscopy in InGaAs films. Spatial imaging of the spin polarization after optical orientation with linearly polarized light shows a superposition of two spin components. An out-of-plane spin component is found, which depends on the polarization direction of the pump beam. We develop a model ascribing the polarization mechanism of these out-of-plane spins to the internal Dresselhaus field. Furthermore, we observe an in-plane spin component with spins aligned antiparallel when propagating in opposite directions away from the laser spot.
This work has been supported by DFG through FOR 912.