Résumé
We report time-resolved Kerr rotation experiments on bulk CdMnTe with very low Mn concentration. We observe spin beatings which are the result of a complex spin dynamics of the d-electrons in the hyperfine field of their nucleus and the tetragonal crystal field. We find the transverse Mn spin relaxation time to increase with the increase of the effective temperature of Mn subsystem. At higher temperatures we measure T2 up to 12 ns, which is much longer than any previously measured values.