Coexistence of superconductivity and antiferromagnetism in the Hubbard model: A phase diagram for finite temperature

Abstract

Abstract The normal paramagnetic, superconducting, antiferromagnetic and simultaneously superconducting and antiferromagnetic states of correlated electrons in the nearly half-filled band have been described by the mean field approach. The Hubbard model has been used as a starting point. A general form of the spin density wave (SDW) order parameter has been proposed. The possibility of coexistence of SDW and superconducting (SC) phases has been confirmed by comparison of free energies. It has been proved that near half-filling superconductivity is suppressed by antiferromagnetism. A finite temperature phase diagram has been presented. It has been shown that SDW cannot enhance the critical temperature of superconductivity. The possible relevance of these results in copper oxides, especially to those where this coexistence was observed, has been discussed.