Hydrostatic pressure effects on spin depolarization dynamics in wurtzite GaN

Abstract

Spin depolarization dynamics of wurtzite GaN under hydrostatic pressure was investigated by combining a time-resolved Kerr rotation spectroscopy with a diamond-anvil cell technique. Upon resonant excitation with bandgap energy, spin polarization of electrons is observed to be robust up to several gigapascals. It is found that the spin depolarization is significantly accelerated due to the generation of non-radiative recombination centers induced by hydrostatic pressure, while the electron spin relaxation time shows a weak dependence on pressure. This observation is attributed to the wide bandgap of wurtzite GaN, which leads to an almost unchanged Rashba spin–orbit coupling within the pressure range of several gigapascals. Based on the D'yakonov–Perel' model, the effects of hydrostatic pressure and biaxial strain induced by the substrate on electron spin relaxation time are estimated in GaN epilayers. These findings provide insights into the underlying mechanism of spin relaxation and are crucial for spin manipulation in the development of GaN-based spintronic devices.