K-Space Gap Anisotropy within the Interlayer Pair-Tunneling Mechanism of High-T C Superconductivity

Abstract

We consider a mean-field approach to a 2D extended Hubbard model for a bilayer superconductor, in presence of coherent interlayer pairtunneling and quenched coherent single particle tunneling. The functional form of the intralayer pairing potential is dictated by the symmetry character of the underlying crystal lattice. This gives rise to a competition between s- and d-wave symmetry, as the chemical potential is increased from the bottom to the top of a realistic band for most cuprates. It allows for mixed-symmetry paired state at temperatures below T c, but never at T c on a square lattice. The interlayer pair-tunneling mechanism contributes to the pairing potential as an effective k-diagonal term, which is responsible of a nonconventional k-dependence of the gap function. We study the evolution of such a gap structure with temperature and with band filling.