Current percolation and the<i>V</i>-<i>I</i>transition in YBa₂Cu₃O₇bicrystals and granular coated conductors

Abstract

There is considerable interest in the dynamics of vortices in granular `coated conductors' consisting of a 2D network of low angle grain boundaries (LAGBs). The V-I characteristic of the conductor is determined by a combination of flux vortex channelling along the grain boundaries and current percolation within the grain network. In this work it is shown that measurements of viscous flow for a YBa2Cu3O7 bicrystal LAGB can be applied in a statistical model that predicts the characteristic V-I response for a particular grain-to-grain dispersion of grain boundary angles.