title: Increasing d-wave superconductivity by on-site repulsion.
abstract: We study, through the variational Monte Carlo technique, an extended Hubbard model away from half filled band density which contains two competing nearest-neighbor interactions: a superexchange J favoring d-wave superconductivity and a repulsion V opposing it. We find that the on-site repulsion U effectively enhances the strength of J while suppressing that of V, thus favoring superconductivity. This result shows that attractions which do not involve charge fluctuations are very well equipped against strong electron-electron repulsion so much to get advantage from it.
authors.affiliation: Istituto Nazionale di Fisica della Materia, Via Beirut 2-4, I-34014 Trieste, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Plekhanov
authors.forename: S
authors.initials: S
authors.lastname: Sorella
authors.forename: M
authors.initials: M
authors.lastname: Fabrizio