Spread of critical currents in thin-film YBa 2Cu 3O 7− x bicrystal junctions and faceting of grain boundary

Abstract

A spread of the critical currents in a series array of 100 YBa 2Cu 3O 7− x bicrystal junctions has been studied by laser scanning microscopy. The values of the critical current I c of individual junctions in the array have been obtained by focusing a laser beam on each junction and measuring the current through the array at which the maximum laser-induced voltage response has appeared on the array. The distribution of critical currents in logarithmic scale was close to a Gaussian one. The I c-spread has been found to increase with the increase of misorientation angle of bicrystal substrate and the decrease of the width of the junctions in the array.