Effect of diffusive boundaries on surface superconductivity in   unconventional superconductors
  Boundary conditions for a superconducting order parameter at a diffusive scattering boundary are derived from microscopic theory. The results indicate that for all but isotropic gap functions the diffusive boundary almost completely suppresses surface superconductivity in the Ginzburg-Landau regime. This indicates that in anisotropic superconductors surface superconductivity can only be observed for surface normals along high symmetry directions where atomically clean surfaces can be cleaved. 
D.F. Agterberg and M. B. Walker