Magnetic properties of the Anderson model with particle-hole attraction

Abstract

The periodic Anderson model (PAM) has been proved to be very rich, capable of describing diverse phenomena such as the moment localization, mixed valence, heavy fermions etc. In this model the number of holes in the localized states increases as the mixed valence regime is approached. Therefore, the magnetic properties of the model are studied after supplementing PAM with an attractive interaction between the localized holes and electrons in the extended states. The model is made tractable by making the mean-field approximation. This results in the renormalization of the model parameters which become temperature dependent. The equations are derived for the average occupation number of the localized states, of the band states and for the excitonic correlation function for both spin directions. A self-consistent solution of these equations leads to the determination of the average valence n f, the spontaneous magnetization m f and the Curie temperature T C. The influence of various model parameters, with particular emphasis on the particle-hole attraction strength, on n f, m f and T C has been studied. The results are summarised in a phase diagram.