SURFACE SUPERCONDUCTIVITY OF SHORT COHERENCE LENGTH SUPERCONDUCTORS

Abstract

Based on the microscopic theory of Valls et al for short coherence length superconductors, the surface critical temperature T-cs is assumed to be higher than the bulk critical temperature T-cb and the term of surface energy is added in the Ginzburg-Landau (GL) free energy. A boundary condition is obtained and used to solve the GL equation exactly under zero magnetic field for various temperatures. Two examples are given. The critical temperature Tc will be enhanced by reducing the thickness of a superconducting thin film. The nucleation field H-c3 (T) is proportional to T-cb - T near T-cb; and H-c3 (T) is also proportional to (T-c - T)(1/2) near Tc.