Thin films of anisotropic superconductors

The effects of boundary scattering in p- and d-wave thin (d≲ξ) superconducting films are studied. Even for specularly reflecting walls, the transition temperature of anisotropic superconductors is monotonically depressed as the thickness decreases and does not exhibit the oscillations characteristic of an ordinary s-wave (isotropic) superconductor. In the presence of a rough boundary, diffusive scattering dramatically reduces $T_c$ resulting in a critical thickness below which the film re- mains normal. In the p-wave (odd parity) case there is a critical roughness above which a finite density of states appears at the Fermi level; d-wave (even parity) superconducting films are always gapless.