Femtosecond time-resolved differential reflectively measurements in Ga1-xMnxAs epitaxial thin films

Magnetic semiconductors such as Ga 1-x Mn x As have attracted a great interest in the last years due to their high potential as advanced-performance materials in optical detection and in novel spintronic devices. The carrier dynamics and the nonlinear optical response in low-temperature-grown GaAs/Ga 1-x Mn x As heterostructures represent an interesting topic much less explored than their electronic transport and/or structural studies. We report our optical investigations of Ga 1-x Mn x As films, grown with different Mn concentrations and subject to annealing conditions, by time-resolved, femtosecond pump-probe, differential reflectivity measurements. The analysis of the carrier relaxation times at low temperatures is presented and discussed according to nonequilibrium theories for electron scattering in magnetic materials.