Single-site approximation for the s-f model in ferromagnetic semiconductors

The ground state phase diagram of the diluted ferromagnetic Kondo-lattice model

We investigate the existence of several (anti-)ferromagnetic phases in the diluted ferromagnetic Kondo-lattice model, i.e. ferromagnetic coupling of local moment and electron spin. To do this we use a coherent potential approximation (CPA) with a dynamical alloy analogy. For the CPA we need effective potentials, which we obtain first from a mean-field approximation. To improve this treatment we use in the next step a more appropriate moment conserving decoupling approach and compare the two methods. The different magnetic phases are modeled by defining two magnetic sub-lattices. As a result we present zero-temperature phase diagrams according to the important model parameters and different dilutions.