Spin relaxation in $n$-type ZnO quantum wells

TL;DR

This study investigates spin relaxation in n-type ZnO quantum wells, revealing temperature and electron density effects, including peaks caused by Coulomb scattering, with relaxation times reaching nanoseconds.

Contribution

It provides a detailed numerical analysis of spin relaxation in ZnO quantum wells considering all relevant scattering mechanisms, highlighting unique temperature and density dependence features.

Findings

Peak in temperature dependence of spin relaxation time at low impurity density

Peak in electron density dependence at low temperature

Spin relaxation time can reach nanoseconds at low temperature and high impurity density

Abstract

We perform an investigation on the spin relaxation for $n$-type ZnO (0001) quantum wells by numerically solving the kinetic spin Bloch equations with all the relevant scattering explicitly included. We show the temperature and electron density dependence of the spin relaxation time under various conditions such as impurity density, well width, and external electric field. We find a peak in the temperature dependence of the spin relaxation time at low impurity density. This peak can survive even at 100 K, much higher than the prediction and measurement value in GaAs. There also exhibits a peak in the electron density dependence at low temperature. These two peaks originate from the nonmonotonic temperature and electron density dependence of the Coulomb scattering. The spin relaxation time can reach the order of nanosecond at low temperature and high impurity density.