High-temperature thermodynamics of the ferromagnetic Kondo-lattice model

We present a high-temperature series expansion for the ferromagnetic Kondo-lattice model in the large coupling limit, which is used to model colossal magnetoresistance (CMR) perovskites. Our results show the expected crossover to Curie-Weiss behavior at a temperature related to the bandwidth. Estimates for the magnetic transition temperatures are in the experimentally observed range. The compressibility shows that the high-temperature charge excitations can be modeled by spinless fermions. The CMR effect itself, however, warrants the inclusion of dynamic effects and cannot be explained by a static calculation. copyright 1997 The American Physical Society