Spin relaxation near the metal-insulator transition: dominance of the Dresselhaus spin-orbit coupling

TL;DR

This paper demonstrates that Dresselhaus spin-orbit coupling is the primary mechanism for spin relaxation in doped semiconductors near the metal-insulator transition, with theoretical results matching experimental data.

Contribution

It introduces a tight-binding model including Dresselhaus hopping terms and shows their dominance in spin relaxation through analytical and numerical methods.

Findings

Dresselhaus coupling dominates spin relaxation in impurity bands.

Theoretical spin-relaxation times agree with experimental measurements.

Analytical and numerical approaches confirm the dominance of Dresselhaus effects.

Abstract

We identify the Dresselhaus spin-orbit coupling as the source of the dominant spin-relaxation mechanism in the impurity band of doped semiconductors. The Dresselhaus-type (i.e. allowed by bulk-inversion asymmetry) hopping terms are derived and incorporated into a tight-binding model of impurity sites, and they are shown to unexpectedly dominate the spin relaxation, leading to spin-relaxation times in good agreement with experimental values. This conclusion is drawn from two complementary approaches employed to extract the spin-relaxation time from the effective Hamiltonian: an analytical diffusive-evolution calculation and a numerical finite-size scaling.