Role of Flux Pinning in High Temperature Superconductors

Abstract

The critical state model with a pinning force independent of flux density is employed to interpret the meas.ured ac magnetic flux response and the weak critical current density of ceramic Y-Ba-Cu-O material. The intergranular (Josephson) vortex pinning is found to be about 108 times weaker than that in conventional type II superconductors.