Scaling of flux pinning with the thermodynamic critical field

A systematic study of flux pinning and the thermodynamic critical field H_c has been undertaken to determine whether H_c is a central factor determining the critical current J_c. Materials that have a fairly wide temperature interval of thermodynamic reversibility are selected so that the thermodynamic critical field can be confidently extrapolated into the irreversible regime. J_c is found to scale with H_c. For a given sample, the J_c/H_c vs H/H_c curves are close to a universal function as temperature changes. In addition, the peak in the pinning force curve also scales with H_c² for a wide variety of samples having quite different transition temperatures.