Laser induced ultrafast demagnetization in diluted magnetic semiconductor nanostructures

We present a dynamical model that reproduces the observed time evolution of the magnetization in diluted magnetic semiconductor films after weak laser excitation. Based on a many-particle expansion of the exact p-d exchange interaction, our approach goes beyond the usual mean-field approximation. Numerical results demonstrate that the hole spin relaxation plays a crucial role for explaining the ultrafast demagnetization processes observed experimentally. The influence of the laser power on the magnetization dynamics is also investigated.