D'yakonov-Perel' spin relaxation in a bilayer with local structural inversion asymmetry

Abstract

The spin relaxation in the D'yakonov-Perel' mechanism is theoretically studied in a symmetric double-quantum-well structure (DQWS) with an intersubband spin-orbit interaction (SOI) due to the local structural inversion asymmetry and the linear-in-wave-number Dresselhaus SOI. It is found that the spin relaxation rate induced by the intersubband SOI exhibits a suppression with $\ensuremath{\omega}{\ensuremath{\tau}}_{p}$ in the Lorentzian form of ${\left(1+{\ensuremath{\omega}}^{2}{\ensuremath{\tau}}_{p}^{2}\right)}^{\ensuremath{-}1}$, where $\ensuremath{\hbar}\ensuremath{\omega}$ is the intersubband energy separation and ${\ensuremath{\tau}}_{p}$ is the momentum relaxation time. The present Lorentzian suppression leads to a crossover with increasing $\ensuremath{\omega}{\ensuremath{\tau}}_{p}$ from the D'yakonov-Perel'-type relaxation (the spin relaxation time ${\ensuremath{\tau}}_{s}\ensuremath{\propto}{\ensuremath{\tau}}_{p}^{\ensuremath{-}1}$) to the Elliott--Yafet-type relaxation (${\ensuremath{\tau}}_{s}\ensuremath{\propto}{\ensuremath{\tau}}_{p}$). It is also shown that the spin relaxation rate in the presence of both the linear Dresselhaus SOI and the intersubband SOI is isotropic with respect to the in-plane spin direction in the present DQWS in contrast to a single quantum well exhibiting an in-plane anisotropy.