The Effect of Magnetic Field on the Critical Current of YBa₂Cu₃O_x Ceramics

Abstract

Three magnetic field ranges corresponding to different critical current density J c behavior have been discovered. They correlate with grain magnetization changes. The first field range corresponds to the grain Meissner phase, the second one to the partial penetration of magnetic fluxoids into a grain, and the third one to the complete vortex penetration. For the first interval, the dependence J c ( H )= J c (0)/[1+( H / H 0 ) 2 ] is valid. The inverse critical current density is shown to depend linearly on the sample cross-section due to the magnetic field self-induced by the flowing current.