Electron Spin Relaxation in Two Polymorphic Structures of GaN

TL;DR

This study investigates electron spin relaxation times in two GaN polymorphs, revealing differences in relaxation behavior and underlying mechanisms, with implications for spintronic applications.

Contribution

It provides a microscopic calculation of spin relaxation times in wurtzite and zinc-blende GaN, highlighting structural effects and relaxation mechanisms.

Findings

Relaxation times are smaller in zinc-blende GaN.

Temperature and magnetic field increase reduce relaxation times.

Wurtzite GaN's relaxation is explained by Elliot-Yafet process at low density.

Abstract

The relaxation process of electron spin in systems of electrons interacting with piezoelectric deformation phonons that are mediated through spin-orbit interactions was interpreted from a microscopic point of view using the formula for the electron spin relaxation times derived by a projection-reduction method. The electron spin relaxation times in two polymorphic structures of GaN were calculated. The piezoelectric material constant for the wurtzite structure obtained by a comparison with a previously reported experimental result was P_pe=1.5 x 10^29 eV/m. The temperature and magnetic field dependence of the relaxation times for both wurtzite and zinc-blende structures were similar, but the relaxation times in zinc-blende GaN were smaller and decreased more rapidly with increasing temperature and magnetic field than that in wurtzite GaN. This study also showed that the electron spin relaxation for wurtzite GaN at low density could be explained by the Elliot-Yafet process but not for zinc-blende GaN in the metallic regime.