Dynamical mean-field study of ferromagnetism in the periodic Anderson model

The ferromagnetic phase diagram of the periodic Anderson model is calculated using dynamical mean-field theory in combination with the modified perturbation theory. Concentrating on the intermediate valence regime, the phase boundaries are established as a function of the total electron density. the position of the atomic level, and the hybridization strength. The main contribution to the magnetic moment stems from the f electrons. The conduction-band polarization is, depending on the system parameters, either parallel or antiparallel to the f magnetization. By investigating the densities of states, one observes that the change of sign of the conduction band polarization is closely connected to the hybridization gap, which is only apparent in the case of almost complete polarization of the f electrons. Finite-temperature calculations are also performed, and the Curie temperature as function of electron density and f-level position are determined. In the intermediate-valence regime, the phase transitions are found to be of second order.