Universal behaviour of Jc(T) and Ueff(J) in YBCO thin films

Systematic measurements of the critical current versus temperature over a range between 10 K ad Tc and of the energy barrier for vortex motion Ueff 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 Jc(T) and Ueff(J) for all YBCO films independent of thin growth conditions, substrates, film thickness and the magnitude of Tc or Jc. We suggest that this behaviour is governed by an intrinsic property of YBCO, the Josephson nanostructures in the a-b planes. (author)