Transport Critical Current Density of Polycrystalline YBCO in Zero Field Cooled and Field Cooled States: A Comparison

Abstract
Magnetic field dependence of transport critical current density (J c) of a polycrystalline YBCO superconductor in field cooled and zero field cooled cases have been studied experimentally. The measured J c value when the sample was cooled in a field (FC) was always larger than that measured for a zero field cooled (ZFC) case in the same magnetic field. We also observe (i) a peak in the field dependence of the ratio of J c in FC case to that of ZFC case and (ii) an anomalous rise in J c in ZFC case with increasing field. These observations are explained as a signature of two types of regions (intergrain and intragrain) in sintered specimens.