Effect of nonequilibrium phonons on hot-electron spin relaxation in n-type GaAs quantum wells

摘要

We study the effect of nonequilibrium longitudinal optical phonons on hot-electron spin relaxation in n-type GaAs quantum wells. The longitudinal optical phonons are driven to nonequilibrium states by electrons under an in-plane electric field. The nonequilibrium phonons then in turn influence the electron spin relaxation properties via modifying the electron heating and drifting. When the longitudinal optical phonons are treated as the nonequilibrium rather than the equilibrium ones, the spin relaxation time is increased since the electron heating is enhanced and hence the electron-phonon scattering is strengthened. Meanwhile, the frequency of spin precession, which is roughly proportional to the electron drift velocity, can be either increased or decreased. The former happens in the case with low electric field and/or high lattice temperature, whereas the latter happens in the case with high electric field and/or low lattice temperature. The nonequilibrium phonon effect is more pronounced when the electron density is high and the impurity density is low.