Transport and recombination through weakly coupled localized spin pairs in semiconductors during coherent spin excitation

Semianalytical predictions for the transients of spin-dependent transport and recombination rates through localized states in semiconductors during coherent electron-spin excitation are made for the case of weakly spin-coupled charge-carrier ensembles. The results show that the on-resonant Rabi frequency of electrically or optically detected spin oscillation doubles abruptly as the strength of the resonant microwave field gamma B-1 exceeds the Larmor frequency separation within the pair of charge-carrier states between which the transport or recombination transition takes place. For the case of a Larmor frequency separation of the order of gamma B-1 and arbitrary excitation frequencies, the charge carrier-pairs exhibit four different nutation frequencies. From the calculations, a simple set of equations for the prediction of these frequencies is derived.