ABSTRACT
This chapter describes continuing optical experiments aimed at elucidating the mechanisms of electron spin relaxation in very high-mobility two-dimensional electron gases (2DEG) in gallium arsenide. The experiments described have led to a modification of this view and to renewed theoretical predictions that are providing new insights into the mechanisms of spin dynamics of 2DEGs. For n-type samples and particularly 2DEGs, the Bir, Aronov, nor Pikusor the Elliott-Yaffetechanism is important. In n-type structures, electron-electron scattering will give a completely different dependence of the spin-relaxation time on both temperature and electron concentration than that which would be predicted by only considering other scattering mechanisms. The practical significance of the difference clearly depends on the relative strengths of the electron-electron scattering and the remaining scattering processes that do affect the mobility. The usual assumption of D’yakonov, Perel’ and Kachorovskii theory has been that the scattering time for randomization of spin precession is closely related to the transport scattering time, which determines the mobility.
