Temperature dependence of the ultrafast photoluminescence kinetics from the magnetic semiconductors CdCr2Se4excited by femtosecond laser pulse

The recombination time of photogenerated carriers in CdCr2Se4has been directly measured as a function of temperature. The relaxation kinetics of carriers has been observed to change above and below the Curie temperature 130 K. A deviation from a monotonic increase in the recombination time is measured as the temperature is lowered toward the Curie temperature. This complex behavior is attributed to the interaction between the short-range spin critical fluctuation of the magnetic ions and the spins of the carriers. The fastest measured recombination time at room temperature is 3.8 ps.