Generalized Elliott-Yafet spin-relaxation time for arbitrary spin mixing

TL;DR

This paper generalizes the Elliott-Yafet theory to include optical phonon interactions, providing a more accurate calculation of spin-relaxation times in materials with spin mixing, demonstrated through numerical analysis of GaAs.

Contribution

It extends previous models to incorporate optical phonons and shows that the conventional Elliott-Yafet formula underestimates spin-relaxation times in spin-mixed systems.

Findings

The generalized formula accurately predicts longer spin-relaxation times.

Conventional Elliott-Yafet underestimates relaxation times in spin-mixed bands.

Numerical results for GaAs validate the improved model.

Abstract

We extend our recent result for the spin-relaxation time due to acoustic electron-phonon scattering in degenerate bands with spin mixing [New J. Phys. 18, 023012 (2015)] to include interactions with optical phonons, and present a numerical evaluation of the spin-relaxation time for intraband hole-phonon scattering in the heavy-hole (HH) bands of bulk GaAs. Comparing our computed spin-relaxation times to the conventional Elliott-Yafet result quantitatively demonstrates that the latter underestimates the spin-relaxation time because it does not correctly describe how electron-phonon interactions change the (vector) spin expectation value of the single-particle states. We show that the conventional Elliott-Yafet spin relaxation time is a special case of our result for weak spin mixing.