Materials science and engineering b-solid state materials for advanced technology vol:126 issue:2-3 pages:107-111
We have investigated the bias-dependent spin relaxation in Cu-CoFe-AlOx-GaAs/AlGaAs-type of Spin-LEDs using microscopic time-resolved magnetization modulation spectroscopy (TIMMS). We observed a significant dependence of the electron spin relaxation time (effects as large as 40%) as a function of applied bias. The additional spin relaxation at non-zero bias is found to scale almost linearly with the injection current, and thereby with the current-induced hole density in the active region. This observation is indicative for a dominant contribution by Bir-Aronov-Pikus (BAP) electron-hole spin-flip scattering. In agreement with this observation, a similar BAP-enhanced spin relaxation shows up at increased laser fluence. From spatio-temporal imaging of spin relaxation, scanning pump and probe beams across the 50 mu m outside of optical window, we found a significant position dependence (lateral effects) of the spin dynamics. (c) 2005 Elsevier B.V. All rights reserved.