Carrier-induced ferromagnetism in a diluted Hubbard model
  Carrier-induced ferromagnetism is investigated in a diluted Hubbard model for ordered impurity arrangements. The delicate competition between particle-hole processes contributing to the spin couplings results in a rich variety of behaviour. The ferromagnetic transition temperature obtained within the spin-fluctuation theory is in good agreement with reported values for $\rm Ga_{1-x} Mn_x N$. 
Sudhakar Pandey and Avinash Singh