Influence of the microbridge width on the transition to the normal state induced by high current densities ramps in YBa2Cu3O7-δ thin films

Abstract

We report current voltage curves (CVC) on c-axis oriented YBa2Cu3O7-δ superconducting thin films patterned in several microbridges of different width and the same width/length ratio (1/10). The microbridge widths range from 5 µm to 100 µm. Our present measurements extend previous experiments performed in our research group to microbridges with different geometries. Measurements of CVC spanned the whole range: from the critical current Jc (when the dissipation starts) to the supercritical current J* (when an abrupt jump to a highly dissipative state occurs). We have found that Jc values do not change for all the microbridges of the same film whereas J* decreases as the microbridge width increases. These findings indicate that near Jc the current is almost uniformly distributed over all the microbridge volume. Moreover, although our results do not exclude an intrinsic origin for the transition to the normal state induced by high current densities, they suggest that J* could be deeply affected by the thermal interchange between the films and their substrates.