Dresden 2011 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 33: Spin-dependent Transport I

HL 33.1: Vortrag

Dienstag, 15. März 2011, 10:15–10:30, POT 251

Time-resolved Kerr detection of acoustic spin transport in GaAs (110) quantum wells — •Alberto Hernández-Mínguez, Klaus Biermann, Snežana Lazić, Rudolph Hey, and Paulo V. Santos — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin, Germany

Surface acoustic waves (SAWs) provide an efficient tool for the transport of spins in semiconductor quantum wells (QWs). The SAW piezoelectric field captures photogenerated electrons and holes in spatially separated locations, thus dramatically increasing the recombination lifetime, and transports them with well-defined velocity. Previous investigations of acoustic spin transport were carried out using spatially resolved photoluminescence, which requires the radiative recombination of the carriers. In this contribution, we demonstrate an alternative spin detection approach based on microscopic Kerr reflectometry in GaAs (110) QWs, where spin dephasing mechanisms associated with spin-orbit interaction result inoperative for electron spins oriented along the growth axis. The spins are generated on the SAW path by a pump laser pulse and are detected by measuring the change δ P in polarization of a probe pulse delayed by τ with respect to the pump. Spatial profiles of δ P during acoustic transport show a peak at x=v_SAWτ, thus revealing the position of the moving spin packet. Measurements under an in-plane applied magnetic field demonstrate the coherent precession of the optically generated electron spins during acoustic transport over several µm, yielding information about the relaxation processes for the acoustically moving spins.