Superconductivity driven by interlayer coupling in strongly correlated electron systems

We study a simple tight-binding, Hubbard-type, model which allows us to investigate the role of interlayer hopping in strongly anisotropic systems. The model consists of Hubbard planes coupled by correlated hopping: tunneling between planes is allowed only if two electrons share the same site. As usual, the on-site interaction U represents the screened Coulomb repulsion. According to BCS mean field theory, this model shows superconductivity with strongly density-dependent transition temperature with a maximum at low doping. The opening of the gap in the excitation spectrum makes the state stable with respect to direct electron hopping between the planes. In the strong coupling limit, the model maps to a system of t-J models with super-exchange interaction between planes. (C) 1999 Elsevier Science B.V. All rights reserved.