Mechanisms of critical current limitation in YBCO thin film structures

Abstract

The limitation of critical current in high Tc superconducting YBCO thin films has a varied nature according to the quality of YBCO films. Our results showed that in strips from granular films the weak links of superconductor–normal metal–superconductor and superconductor–constriction–superconductor types were responsible for critical current limitation. In the YBCO strips with improved (preferential) crystallographic orientation a flux-creep critical current limitation was found and in the highly oriented YBCO strips the Ginzburg–Landau depairing mechanism approximated the critical current limitation for temperature close to Tc.