MEAN-FIELD ANALYSIS OF A MODEL FOR SUPERCONDUCTIVITY IN AN ANTIFERROMAGNETIC BACKGROUND

We study a lattice fermion model for superconductivity in the presence of an anti-ferromagnetic background, described as a fixed external st aggered magnetic field. We discuss the possibility that our model prov ides an effective description of coexistence of anti-ferromagnetic cor relations and superconductivity. and its possible application to high- temperature superconductivity. We also argue that, under certain condi tions, this model describes a variant of the periodic Anderson model f or heavy fermions. Using a path integral formulation we construct mean field equations, which we study in some detail. We evaluate the super conducting critical temperature and show thar it is strongly enhanced by anti-ferromagnetic order. We also evaluate the superconducting gap, the superconducting density of states, and the tunneling conductivity , and show that the most stable channel usually has a d(x2-y2)-wave ga p. (C) 1998 Elsevier Science B.V.