Atomistic pseudopotential theory of spin relaxation in self-assembled In_(1-x)Ga_xAs/GaAs quantum dots at zero magnetic field

摘要

An atomistic pseudopotential calculation of the spin-flip time (T_1) of electrons and holes mediated by acoustic phonons in self-assembled In_(1-x)Ga_x As/GaAs quantum dots at zero magnetic field is presented. At low magnetic field, the first-order process is suppressed, and the second-order process becomes dominant. It is found that the spin-phonon-interaction-induced spin relaxation time is 100-221 s for electrons, and 4.4-60 ms for holes at 4.2 K. The calculated hole-spin relaxation times are in good agreement with recent experiments, which suggests that the two-phonon process is one of the main relaxation mechanisms for hole-spin relaxation in the self-assembled quantum dots at zero field. The structural and alloy composition effects on the spin relaxation in the quantum dots are clarified.