Comparison of current–voltage characteristics of YBa2Cu3O7−δ melt-textured samples and films up to the superconducting normal transition

Current-voltage characteristics (CVCs), up to current densities several times the critical current density Jc, are presented for melt-textured samples and films of YBa2Cu3O7-delta, at various temperatures. The results for both kind of samples present an overall common behavior: above Jc, electric field E increases with current density J in a non-linear but smooth way, up to a particular point (J*,E*), at which an abrupt transition to a highly dissipative regime takes place. The only significant difference between the two set of curves is that both E and J along the CVCs are two order of magnitude higher in films, this including E* and J*. From the analysis of the data, a parallel variation of the electric field with current, and a common value of the ratio J*/Jc has been found in both CVCs sets. These results suggest a common origin of the abrupt transition in both kind of samples, in spite of the scaling difference in E and J.