Low-temperature spin relaxation in n-type GaAs

TL;DR

This study investigates low-temperature electron spin relaxation in n-GaAs across various doping levels, revealing different relaxation mechanisms in metallic and insulating phases near the metal-insulator transition.

Contribution

It provides experimental insights into the spin relaxation mechanisms in n-GaAs near the metal-insulator transition, highlighting the change from Dyakonov-Perel to exchange and hyperfine interactions.

Findings

Spin lifetime peaks near the MIT at n_D = 2x10^16 cm^{-3}.

Dyakonov-Perel mechanism dominates in the metallic phase.

Exchange and hyperfine interactions govern relaxation in the insulating phase.

Abstract

Low-temperature electron spin relaxation is studied by the optical orientation method in bulk n-GaAs with donor concentrations from 10^14 cm^{-3} to 5x10^17 cm^{-3}. A peculiarity related to the metal-to-insulator transition (MIT) is observed in the dependence of the spin lifetime on doping near n_D = 2x10^16 cm^{-3}. In the metallic phase, spin relaxation is governed by the Dyakonov-Perel mechanism, while in the insulator phase it is due to anisotropic exchange interaction and hyperfine interaction