Time-resolved differential transmission in MOVPE-grown ferromagnetic InMnAs

We measured time-resolved differential transmission in InMnAs for different pump/probe schemes as a function of temperature, laser fluence, and external magnetic field. We observed tunability of the carrier relaxation time. In addition, we found that the sign of the differential transmission changed as a function of probe wavelength. The electronic structure for InMnAs was calculated for B = 0, using an eight-band k.p model, which includes conduction and valence band mixing as well as coupling of electrons and holes to the magnetic Mn impurities. This allows us to explain some of the carrier dynamics and the sign changes in the differential transmission.