Capillary-wave effects at critical wetting in type-I superconductors

We discuss the effect of fluctuations of the superconductor-normal (SC/N) interface on the (short-range) critical wetting transition in type-I superconductors. Functional renormalization of a standard effective interface Hamiltonian shows that the fluctuation regimes found for short-range critical wetting in conventional fluid systems appear in superconductors with slight modifications. Because the fluctuation parameter omega approximately 1/(1-sqrt[2]kappa) depends on the Ginzburg-Landau parameter kappa, strong fluctuation effects would be expected in the limit kappa-->1/sqrt[2]. However, the capillary-wave spectrum of the SC/N interface has an unusual form due to a relevant magnetic field contribution which suppresses long wavelength fluctuations, invalidating conclusions drawn from the standard effective interface Hamiltonian, and validating the results of mean-field theory.