Spin relaxation in the impurity band of a semiconductor in the external magnetic field

Spin relaxation in the impurity band of a 2D semiconductor with spin-split spectrum and hyperfine interaction in the external magnetic field is considered. Two contributions to the spin relaxation are shown to be relevant: the one given by optimal impurity configurations with the hop-waiting time inversely proportional to the external magnetic field and another one related to electron motion over large distances. The average spin relaxation rate is calculated.