Mechanism for phase separation in cuprates and related multiband systems

A two-band Hubbard model in the limit of strong on-site Coulomb repulsion is used to describe the band structure and phase separation (PS) in strongly correlated electron systems with a special emphasis on cuprate superconductors. The PS corresponding to the inhomogeneous charge density occurs in such a system due to the redistribution of charge carriers between the bands. This mechanism does not require any magnetic interaction or intersite Coulomb repulsion. The interband hybridization gives rise to a peak in the electron density of states and, in the PS state, the Fermi level in one of the phase is located near this peak. The resulting charge density redistribution can affect the dependence of the superconducting critical temperature T-c on the doping level.