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 ofthe 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 µm outside of optical window, we found a significant position dependence (lateral effects) of the spin dynamics.
|Title of host publication||Visit to IMEC; Leuven, Belgium (22 nov 2004)|
|Publication status||Published - 2004|