Disordered Kondo-lattice model: Extension of coherent potential approximation

An extension of coherent potential approximation to analyze the single-particle spectra of disordered Kondo-lattice model (KLM) to get the interconnected electronic and magnetic properties of "local-moment" systems such as diluted ferromagnetic semiconductors (DMS) is proposed. Electron scattering by the magnetic ions, which are randomly distributed over the crystal volume, is taken into account as well as the peculiarities of the exchange interaction under the single-scattering act in KLM. The coupling of the localized magnetic moments due to the itinerant electrons (holes) is treated by a modified Ruderman-Kittel-Kasuya-Yosida-theory, which maps the KLM onto an effective Heisenberg model. We discuss in detail the dependencies of the Curie temperature on the concentration x of magnetic ions, the carrier concentration n, the exchange coupling J, and the crystal-field parameters: lambda(AA), lambda(MM), and lambda(AM). The latter play a crucial role for understanding and controlling the Curie temperature of DMS.