Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 3: III-V-Compounds: GaAs and related Materials
HL 3.5: Talk
Monday, March 14, 2011, 11:15–11:30, POT 151
Optical detection of electrically-injected spin-polarization — •Roland Völkl1, Tobias Korn1, Andreas Einwanger1, Mariusz Ciorga1, Dieter Schuh1, Werner Wegscheider2, Dieter Weiss1, and Christian Schüller1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg — 2ETH Zürich,8093 Zürich, Schweiz
An essential issue of spintronics is an effective spin injection into semiconductors. Here, we present experiments in which spin-polarized electrons are injected into n-bulk GaAs using a p+-(Ga,Mn)As/n+-GaAs Esaki diode structure.
To probe such a spin polarization, the Hanle-MOKE technique is applied. Hereby the originally in-plane oriented spins are rotated out of the plane by applying a magnetic field. The spin component perpendicular to the sample plane is measured by detecting the Kerr rotation of a linearly polarized laser. The laser beam is focused through a microscope objective. Thus, a spot size around 1um is achieved. While moving the sample under the laser spot the spin polarization can be mapped. 1D as well as 2D mappings show a diffusion length of about 10 um. The spin polarization was also probed at a fixed position depending on the bias of the Esaki diode. The injected spin-polarized electrons polarize the nuclei via hyperfine interaction. By using a circularly polarized laser, additional, optically-injected spin-polarized electrons can be used to probe the local nuclear fields. Financial support by the DFG via SFB 689 is gratefully acknowledged.