Spin Dynamics Controlled by Spin-Dependent Recombination in GaAsN alloys at Room Temperature.

We report on both experimental and theoretical study of conduction-electron spin polarization dynamics achieved by pulsed optical pumping at room temperature in GaAs1-xNx alloys with a small nitrogen content (x = 2.1, 2.7, 3.5%). It is found that the photoluminescence (PL) circular polarization reaches 40–45% and this giant value persists within 2 ns. The results are explained by spin-dependent capture of free conduction electrons on deep paramagnetic centers. We have developed a nonlinear theory of spin dynamics in the coupled system of spin-polarized free and localized carriers that describes the experimental dependencies, in particular, electron spin quantum beats observed in a transverse magnetic field. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]