SuperfluidB3at a rough surface: Density of states in the randomly-rippled-wall model

Abstract

The density of states for superfluid ${}_{}{}^3{}_{}{}^{}\mathit{B}$ at a rough bounding surface is calculated from quasi-classical equations using full nonlinear boundary conditions and the ‘‘randomly-rippled-wall’’ surface model. Increased surface roughness leads to a substantially enhanced total density of states at subgap energies as well as to a more complicated spectrum structure. The calculation provides a strong affirmation of the boundary-condition validity and demonstrates the ready applicability of nonlinear boundary conditions.