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 $H_c^2$ for a wide variety of samples having quite different transition temperatures.