Superconductivity with angular dependent coupling: stripes, Coulomb repulsion and enhanced Tc

Abstract

We have analysed the effect of intrinsic doping inhomogeneity and the presence of stripes in high-T_c superconductors on coupling \lambda by using a simple analytically solvable model with an angular dependent \lambda (\phi) represented by a square-well form. We have found that the introduction of the Coulomb repulsion \lambda_C, increasing the ''contrast'' | \lambda | + | \lambda_C |, or the depth of the angular modulation of \lambda (\phi), leads to a remarkable enhancement of T_c. This effect can be optimized by combining attractive (\lambda <0) and repulsive (\lambda >0) interactions along stripes and perpendicular to them.