SUPERCONDUCTIVITY AND ANTIFERROMAGNETISM FOR AN EXTENDED HUBBARD HAMILTONIAN - ROLE OF CORRELATED HOPPING IN A SINGLE-BAND MODEL

An extended Hubbard model for a single band, including Coulomb repulsi on and correlated hopping between nearest neighbors, is studied using a generalized mean-field approach. Antiferromagnetism and superconduct ivity are probed for arbitrary occupation number, near and away from h alf filling. Binding of pairs in the superconducting state of this pur ely repulsive model is mediated by the correlated hopping in the form of a covalent-bond configuration, with partial intrasite and intersite pairings. A region of coexistence is conjectured, the superconductivi ty being suppressed by the saturation of the staggered magnetic moment . Singlet superconducting nonmagnetic states are obtained for the almo st-empty- or full-band cases. On the other hand, antiferromagnetism in duces mixed s- and p-type superconductivities in the neighborhood of h alf filling.