In a diluted magnetic semiconductor system, the exchange interaction between magnetic impurities has two independent components: direct antiferromagnetic interaction and ferromagnetic interaction mediated by charge carriers. Depending on the system parameters, the ground state of the system may be ordered either ferromagnetically or randomly. In this paper we use percolation theory to find the ferromagnetic transition temperature and the location of the quantum critical point separating the ferromagnetic phase and a valence-bond glass phase.

• Received 25 February 2004

DOI:https://doi.org/10.1103/PhysRevB.70.115216