Effect of Ionized Impurity Screening on Spin Decoherence at Low and Intermediate Temperatures in GaAs

TL;DR

This study investigates how charged impurity screening affects spin decoherence in n-type GaAs, emphasizing the importance of second order Born approximation for accurate spin relaxation time predictions at low to intermediate temperatures.

Contribution

It demonstrates that second order Born approximation significantly shortens predicted spin relaxation times compared to first order, refining the modeling of impurity screening effects in GaAs.

Findings

Second order Born approximation reduces spin relaxation times by hundreds of picoseconds.

First Born approximation overestimates relaxation times by over 30%.

Results align with Dyakonov-Perel theory including impurity interactions at T > 50 K.

Abstract

We study the effect of charged impurity screening on spin decoherence in bulk {\it n}-type GaAs, and analyse in details the effect of the use of different Born approximations applied to a linearized Thomas-Fermi screening theory. The spin relaxation times are calculated by ensemble Monte Carlo techniques, including electron-electron, electron-impurities, and electron-phonons scattering. We carefully choose a parameter region so that all the physical approximations hold, and, in particular, a Yukawa-type potential can be used to describe the screened Coulomb interaction and the Born series converges. Our results show that including the second order Born approximation yields much shorter spin relaxation times compared to the commonly implemented first Born approximation: spin relaxation times may be reduced by hundreds of picoseconds, with the first Born approximation overestimating results by 30% or more for a large region of parameters. Though our ensemble Monte Carlo simulations include electron-electron and electron-phonon interactions, when considering low to intermediate carrier densities and $T > 50 $ $\mathrm{K}$, but $T$ smaller than the Fermi temperature, our results are in good agreement with Dyakonov-Perel theory when this includes electron-impurity interactions only, which supports this to be the most relevant scattering mechanism for bulk GaAs in this low-intermediate temperature regime.