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

We have analyzed the effect of intrinsic doping inhomogeneity and the presence of stripes in high-T-c superconductors on coupling constant 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 for certain angles 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 (C) > 0) interactions along stripes and perpendicular to them.