A simplified correlated variational approach to ferromagnetism in the two electron T-U-V-J model

Abstract

The dynamics of the interacting electronic pair is examined in this work by the single band t-U-V-J model, which is hoped to provide an insight into the interaction mechanism of ferromagnetic metals. Although the Hubbard model (which is the t-U Hamiltonian) was originally proposed as a simply model to describe the physics of ferromagnetic metals, the various studies in the literature show, however, that the model usually favours antiferromagnetism. Three natural routes to go beyond the original Hubbard model are to enhance the kinetic part, include other interaction matrix elements within the single band model or include band degeneracy that allows intra-atomic exchange. We have taken the second route in this work by investigating in all three dimensions, lattices with periodic boundary conditions. The mathematical method is the simplified correlated variational approach (CVA) recently developed by us. The results obtained provide an insight into the behaviour of ferromagnetic metals in the t-U-V-J model. In particular, the parameter space for the occurrence of a transition from an antiferromagnetic phase to a ferromagnetic phase is discussed.

Nigerian Journal of Physics Vol. 16(2) 2004: 125-130