Spread of critical currents in thin-film YBa_2Cu_3O_(7-x) bicrystal junctions and faceting of grain boundary

摘要

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.