Dependence of quantum kinetic effects in the spin dynamics of diluted magnetic semiconductors on the excitation conditions

摘要

Non-Markovian quantum kinetic features, that cannot be captured by rate equations, have been predicted theoretically in the spin dynamics in diluted magnetic semiconductors excited with a circularly polarized laser. In order to identify situations which are most promising for detecting the genuine quantum kinetic effects in future experiments, we study numerically the strength of these effects for a number of different excitation conditions. In particular, we show that laser pulse durations of the order of the spin-transfer rate or longer are well suited for studying the non-Markovian effects. Furthermore, in the presence of an external magnetic field, the quantum kinetic theory predicts a significantly different stationary value for the carrier spin polarization than Markovian rate equations, which can be attributed to the build-up of strong carrier-impurity correlations.