Low-temperature spin relaxation in n-type GaAs

Low-temperature electron-spin relaxation is studied by the optical orientation method in bulk n-GaAs with donor concentrations from 10¹⁴ cm^-3 to 5×10¹⁷ cm^-3. A peculiarity related to the metal-to-insulator transition is observed in the dependence of the spin lifetime on doping near n_D=2×10¹⁶ 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