Spin noise of localized electrons: Interplay of hopping and hyperfine interaction

The theory of spin fluctuations is developed for an ensemble of localized electrons taking into account both hyperfine interaction of electron and nuclear spins and electron hopping between the sites. The analytical expression for the spin noise spectrum is derived for arbitrary relation between the electron spin precession frequency in the field of the nuclear fluctuation and the hopping rate. An increase in the hopping rate results in the drastic change of the spin noise spectrum. The effect of an external magnetic field is briefly addressed.