Universal behaviour of and in YBCO thin films

Abstract

Systematic measurements of the critical current versus temperature over a range between 10 K ad and of the energy barrier for vortex motion versus current density were performed for ten YBCO thin films made by different deposition methods in various laboratories. A new technique, which uses ring-shaped samples and a scanning Hall probe, has been developed to study thin film properties. The results imply a universal behaviour of and for all YBCO films independent of thin growth conditions, substrates, film thickness and the magnitude of or . We suggest that this behaviour is governed by an intrinsic property of YBCO, the Josephson nanostructures in the a-b planes.