Phase separation and critical phenomena in the charge ordered system

This study is devoted to the phase separation problem in the charge ordered system, presented in a possibly simplest model form. The extended Hubbard model in the atomic limit (t→0) on a square lattice is analysed using Monte Carlo simulation for the grand canonical ensemble. The model exhibits very rich structure of the phase diagram at finite temperatures as well as in the ground state. Besides the commensurate types of charge order one can observe a mixed phase in T>0 and states with phase separations or stripes in low temperatures. The results show thus a possible classical nature of the phase separation and striped states for charge order.