Normal-superconducting transition induced by high current densities in YBa2Cu3O7-d melt-textured samples and thin films: Similarities and differences

摘要

Current-voltage characteristics of top seeded melt-textured YBa2Cu3O7-d arepresented. The samples were cut out of centimetric monoliths. Filmscharacteristics were also measured on microbridges patterned on thin filmsgrown by dc sputtering. For both types of samples, a quasi-discontinuity orquenching was observed for a current density J* several times the criticalcurrent density Jc. Though films and bulks much differ in their magnitude ofboth Jc and J*, a proposal is made as to a common intrinsic origin of thequenching phenomenon. The unique temperature dependence observed for the ratioJ*/Jc, as well as the explanation of the pre-quenching regime in terms of asingle dissipation model lend support to our proposal.