Two kinds of spin precession modes in diluted magnetic semiconductors
  Time-resolved Kerr rotation experiments show that two kinds of spin modes exist in diluted magnetic semiconductors: (i) coupled electron-magnetic ion spin excitations and (ii) excitations of magnetic ion spin subsystem, which are decoupled from electron spins. The latter modes exhibit much longer spin coherence time and require a description, which goes beyond the mean field approximation. 
M. Vladimirova, S. Cronenberger, P. Barate, D. Scalbert, F. J. Teran,   A. P. Dmitriev