EFFECT OF RANDOMLY DISTRIBUTED ANISOTROPIC VORTICES ON THE CRITICAL-CURRENT OF A LAYERED SUPERCONDUCTOR

We have studied the magnetic field dependence of the c-axis critical c urrent of a layered superconductor when a pinned, disordered lattice o f anisotropic vortices parallel to the superconducting planes is prese nt. The model employed is based on the Josephson coupling picture of l ayered superconductors. In this case the Josephson phase between adjac ent layers varies randomly along the superconducting planes and its sp atial correlations determine the value of an average critical current scale. We show that under these conditions the usual Fraunhofer oscill ations are absent and this critical current is proportional to exp(-H- ext/(H) over tilde(0)), where (H) over tilde(0) is crucially determine d by the anisotropy and depends weakly on the size of the superconduct or. The relevance of our results to transport properties recently obse rved in the high-T-c cuprates is discussed. (C) 1997 Elsevier Science B.V.