Depairing critical currents and self-magnetic field effects in submicron YBa2Cu3O7−δ microbridges and bicrystal junctions

Abstract

We report on depairing critical currents in submicron YBa 2 Cu 3 O 7-d microbridges. A small-angle bicrystal grain boundary junction is used as a tool to study the entrance of vortices induced by a transport current and their influence on the I-V curves. The interplay between the depairing and the vortex motion determines a crossover in the temperature dependence of the critical current. The high entrance field of vortices in very narrow superconducting channels creates the possibility of carrying a critical current close to the depairing limit determined by the S-¢ S -S nature of the small-angle grain boundary junction.

Resistive state triggered by vortex entry in YBa 2 Cu 3 O 7−δ nanostructures

“…and from the Bardeen expression for the temperature dependence of the depairing current density J d ðTÞ / 1 À ðT=T C Þ 2 3=2 [22], characteristic of our nanowires [15] and of YBCO nanowires reported in literature [23], resulting in nðTÞ ¼ n 0 1 À ðT=T C Þ 2 À1=2 , which is valid in the full temperature range. Since our wires are covered by a gold capping layer acting as a shunt, the final resistance can be expressed as:…”

Influence of thickness, width and temperature on critical current density of Nb thin film structures

“…The temperature dependence of the critical current density j C (T) in thin film superconducting strips was in focus of numerous theoretical [1][2][3] investigations and experimental works in low-and high-T C superconductors [4,5]. Additionally, this interest is warming up by a broad range of applications of thin superconducting films used for the development of fast and sensitive detectors [6] and mixers [7] of radiation.…”