Photo-induced anomalous Hall effect in GaAs:MnAs granular films

We investigated the temperature-dependent Hall resistance and magnetization of the semiconductor/ferromagnetic hybrid structure of GaAs:MnAs granular films under dark and laser irradiated conditions. Under the laser irradiation with the energy above the band gap energy of GaAs, negative large Hall resistance due to the anomalous Hall effect was observed below the blocking temperature Tb of the MnAs clusters. The intrinsic photo-induced magnetization of the MnAs clusters was, however, hardly observed. These results indicate that the blocking phenomena correlate with the photo-induced anomalous Hall resistance of the GaAs:MnAs granular films. Therefore, the magnetic interaction between the photo-induced carriers and the blocked magnetization of the MnAs clusters plays an important role in the photo-induced phenomena in the GaAs:MnAs granular films.