Quasi-classical theory of rough surface effects on unconventional BCS states

Abstract

We present a quasi-classical theory of rough surface effects on unconventional BCS pairing states. We reinterpret and generalize the randomly rippled wall model for rough surfaces such that can describe the surface scattering ranging from the specular limit to the diffusive limit. We give a formal solution of the quasi-classical Green's function which already satisfies the boundary condition in a slab geometry. In the diffusive limit, our result correctly recovers the diffusive boundary condition for the GL equation in thep-wave state given by Ambegaokar, deGennes and Ranner. Some applications top-wave andd-wave states are discussed.