Normal-superconducting transition induced by high current densities inYBa2Cu3O7−δmelt-textured samples and thin films: Similarities and differences

Current-voltage characteristics of top-seeded melt-textured YBa 2 Cu 3 O 7 - δ are presented. The samples were cut out of centimetric monoliths. Films characteristics were also measured on microbridges patterned on thin films grown by dc sputtering. For both types of samples, a quasidiscontinuity or quenching was observed for a current density J* several times the critical current density J c . Though films and bulks differ much in their magnitude of both J c and J*, a proposal is made as to a common intrinsic origin of the quenching phenomenon. The unique temperature dependence observed for the ratio J*/J c , as well as the explanation of the prequenching regime in terms of a single dissipation model, lends support to our proposal.