Distribution of pinning energies and the resistive transition in superconducting films.

Abstract

The effect of the distribution of pinning energies on the current-voltage characteristics, magnetic flux creep, and critical currents of superconducting films in a transversal magnetic field H has been considered. In the case of macroscopic inhomogeneities of the pinning forces, the flux creep has been formulated as a percolation transition in the vortex system. The model proposed gives the strong dependence of the critical current on H at low H in the absence of weak links in a superconductor, the increase of the flux-creep activation energy with temperature T at low T and H, and the nonlogarithmic time decay of the magnetization in the flux-creep regime.