Magnetic features near filled impurity band in diluted magnetic semiconductors

The antiferromagnetic-ferromagnetic competition in a diluted magnetic semiconductor is discussed. In a virtual-crystal approximation, the active magnetic ions in the system are assumed to distribute homogeneously, and the quantum magnetic correlations are described in the Kondo lattice model involving local disorder. In the framework of the dynamical mean-field theory, we deliver the signatures of the static magnetic susceptibility function and the B-1g channel Raman response adapting to the model. At low temperatures, one finds the antiferromagnetic instability against the ferromagnetic state when the impurity band is nearly filled. For a completely filled impurity band system, the antiferromagnetic state is stabilized in the case of sufficiently large magnetic exchanges. The effect of the thermal fluctuations on the phase competition is also discussed. Analyzing the B-1g channel Raman spectrum attributes a competition between the short-range magnetic order and the short-wavelength excitation in the filled impurity band paramagnetic state.