On the phase diagram of the zero-bandwidth extended Hubbard model with   intersite magnetic interactions for strong on-site repulsion limit
  In this report we have analyzed a simple effective model for a description of magnetically ordered insulators. The Hamiltonian considered consists of the effective on-site interaction (U) and the intersite Ising-like magnetic exchange interaction (J) between nearest neighbors. For the first time the phase diagrams of this model have been determined within Monte Carlo simulation on 2D-square lattice. They have been compared with results obtained within variational approach, which treats the on-site term exactly and the intersite interactions within mean-field approximation. We show within both approaches 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). 
Szymon Murawski, Konrad Kapcia, Grzegorz Paw{\l}owski, Stanis{\l}aw   Robaszkiewicz (Electron States of Solids Division, Fac...
cond-mat.str-el cond-mat.stat-mech