Local moments in the Hubbard model

Abstract

Using the cluster Bethe lattice method the author formulates the quasi-spin model for itinerant magnetism in order to investigate the coupling between charge and spin fluctuations. Three ordering parameters are introduced: the concentration of up moments, the short-range and long-range spin correlations. Within this model it is shown that the introduction of short-range order can decrease the Curie temperature. The charge transfer between sites with up and down moments which can be of several tenths of an electron indicates that inter-atomic Coulomb and exchange interactions cannot be neglected in this model.