Relaxation mechanism for electron spin in the impurity band of n-doped semiconductors

TL;DR

This paper introduces a new mechanism for electron spin relaxation in n-doped semiconductors near the metal-insulator transition, emphasizing the role of spin-orbit interaction and impurity band hopping.

Contribution

It develops a tight-binding model incorporating spin-orbit effects to explain spin relaxation, aligning theoretical estimates with experimental data.

Findings

Spin lifetime is significantly large due to small spin-flip hopping amplitudes.

Estimated spin lifetime matches experimental order of magnitude.

The mechanism must be considered in spin relaxation models for impurity bands.

Abstract

We propose a mechanism to describe spin relaxation in n-doped III-V semiconductors close to the Mott metal-insulator transition. Taking into account the spin-orbit interaction induced spin admixture in the hydrogenic donor states, we build a tight-binding model for the spin-dependent impurity band. Since the hopping amplitudes with spin flip are considerably smaller than the spin conserving counterparts, the resulting spin lifetime is very large. We estimate the spin lifetime from the diffusive accumulation of spin rotations associated with the electron hopping. Our result is larger but of the same order of magnitude than the experimental value. Therefore the proposed mechanism has to be included when describing spin relaxation in the impurity band.