PHOTOINDUCED MAGNETISM IN THE FERROMAGNETIC SEMICONDUCTORS

Abstract

We study the enhancement of the magnetic transition temperature Tc due to incident light in ferromagnetic semiconductors such as EuS. The photoexcited carriers mediate an extra ferromagnetic interaction due to the coupling with the localized magnetic moments increasing the Tc. The Hamiltonian consists of a Heisenberg model for the localized moments and an interaction term between the photoexcited carriers and the localized moments. The model predicts a small enhancement of the transition temperature, about a fraction of a degree K, in semi-quantitative agreement with the experiments.