Properties of extended Hubbard models with anisotropic spin-exchange interaction (original) (raw)

The phase diagrams and electron orderings of the half-filled extended Hubbard models with anisotropic spin-exchange interactions (J ⊥ , J || ) are studied. The cases of ferromagnetic (J α < 0) and antiferromagnetic (J α > 0) exchange couplings are considered for repulsive on-site interaction (U ≥ 0). The analysis of these t-U-J || -J ⊥ models is performed for d-dimensional hypercubic lattices including d = 1 and d = ∞ by means of the (broken symmetry) HFA supplemented, for d = ∞, by the slave-boson mean-field method. The basic features of the derived phase diagrams are discussed.