E-J Characteristics and Distribution of Local J c for Melt-Textured Grown Bulk YBa 2 Cu 3 O 7 under High Magnetic Fields

In order to evaluate the distribution of flux pinning for a melt-textured grown bulk YBa 2 Cu 3 O 7 under magnetic fields, the E - J properties for samples prepared under various magnetic fields were measured. The measured E - J properties were analyzed on the basis of a local J c distribution model proposed by Yamafuji and Kiss [K. Yamafuji and T. Kiss: Physica C 290 (1997) 9]. The distribution of local J c was found to narrow continuously with increasing magnetic field applied to the melt growth process, independent of the critical current density. The weak links at subdomain boundaries were considered to improve as a result of the change in crystallinity.