Nonequilibrium electron spin relaxation in n-type doped GaAs sample

Abstract

Non-equilibrium electron spin relaxation in a n-type doped GaAs bulk semiconductor is investigated. We use a semiclassical Monte Carlo approach by considering multivalley spin dynamics of drifting electrons. Spin relaxation is considered through the D'yakonov-Perel mechanism, which is the dominant process in III-V semiconductors. An analytical expression for the inhomogeneous broadening of spin precession vector is derived by taking into account the effect of the electric field and the doping density. The inclusion of electron-electron scattering has the effect of increasing both the spin lifetime and the depolarization length. In particular, we find a non-monotonic trend with the maximum of both the spin lifetime and the depolarization length, as a function of the lattice temperature. This peculiar behavior, which is due to the nonlinear spin-lattice interaction through the phononic thermal bath, is akin to the noise-enhanced stability phenomenon. Moreover, for lattice temperatures up to 77 K the electron spin lifetime slightly increases with the doping density, while the spin depolarization length shows a decreasing behaviour. For electic field amplitudes higher than the threshold field (Gunn field), the spin lifetime increases with the lattice temperature. Our numerical findings are validated by a good agreement with the available experimental results.