Murawski, SzymonKapcia, KonradPawłowski, GrzegorzRobaszkiewicz, Stanisław2013-09-022013-09-022012-06Acta Physica Polonica A, Vol. 121, No. 5-6, 1035-1037 (2012)0587-4246http://przyrbwn.icm.edu.pl/APP/PDF/121/a121z5p13.pdfhttp://hdl.handle.net/10593/7700This is an author-created, un-copyedited version of an article accepted for publication in Acta Physica Polonica A. The Version of Record is available online at http://przyrbwn.icm.edu.pl/APP/PDF/121/a121z5p13.pdfIn 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).enmagnetic orderingsphase separationsextended Hubbard modelatomic limitMonte Carlo simulationsArtykuł