1007.1147 (Waldemar Kłobus et al.)

Magnetic orderings and phase separations in the zero-bandwidth limit of
the extended Hubbard model with intersite magnetic interactions    [PDF]

Waldemar Kłobus, Konrad Kapcia, Stanisław Robaszkiewicz

A simple effective model for a description of magnetically ordered insulators is analysed. The tight binding Hamiltonian consists of the effective on-site interaction (U) and intersite magnetic exchange interactions (Jz, Jxy) between nearest-neighbours. The phase diagrams of this model have been determined within the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. We show that, depending on the values of interaction parameters and the electron concentration, the system can exhibit not only homogeneous phases: (anti-)ferromagnetic (F) and nonordered (NO), but also phase separated states (PS: F-NO).

View original: http://arxiv.org/abs/1007.1147