Ultrafast dynamics of the photo-induced magneto-optical Kerr effect in CdTe at room temperature

A time-resolved, all-optical technique based on the photo-induced magneto-optical Kerr effect is applied to the spectral study of the sub-picosecond, room temperature spin dynamics in CdTe between 1.44 and 1.63 eV. Two relaxation processes with respective; decay times of up to 200 ii; and 2.5 ps are distinguished. While the longer one is attributed to electron-spin relaxation, several processes such as the redistribution of electrons in the conduction band or exciton ionization near the band gap are believed to take place on the timescale of the faster one. A change of the spectral dependence of the Kerr effect from a paramagnetic like to a diamagnetic like regime during this faster relaxation is observed and discussed.