Spin relaxation in a quantum well by phonon scatterings

Abstract

The spin relaxation due to the spin-orbit interaction (SOI) is studied theoretically in a quantum well with electrons occupying only the ground subband. First, it is shown that the coefficient of the Rashba SOI is proportional to ${b}_{\mathrm{off}}\ensuremath{-}1$, in which the parameter ${b}_{\mathrm{off}}$, determined by the band offsets and the band gaps, passes through unity, for example, by changing $x$ in ${\mathrm{Ga}}_{0.47}{\mathrm{In}}_{0.53}\mathrm{As}$(well)/${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{y}{\mathrm{Sb}}_{1\ensuremath{-}y}$(barrier). Second, it is derived that the transition matrix element of each spin-flip phonon scattering has the same proportionality factor ${b}_{\mathrm{off}}\ensuremath{-}1$, in addition to the impurity scattering previously studied by the same authors [Phys. Rev. B 89, 075314 (2014)]. These findings suggest the possibility of strongly suppressing the spin-relaxation rate by choosing appropriate materials.