Berechnung des oberflächensenkrechten kritischen Magnetfeldes für supraleitende Filme

Abstract

On the basis of the BCS theory a simplified system of equations for the calculation of the perpendicular critical magnetic field,H _c⊥, for superconducting films is derived with the help of “the method of the correlation function”, developed by Lüders. In the vicinity ofT=T _c for all film thicknesses and mean free paths the problem becomes mathematically equivalent to the calculation of the residual resistance of the film. The results are in good agreement with the experiments of Harper and Tinkham and of others. Further limiting cases are investigated: on the one hand specular reflection and weakly diffuse surface scattering, on the other hand diffuse reflection and very thin films.