Spatial variation in magnetic properties within large-grain Nd-Ba-Cu-O/Ag

Authors investigate the spatial variation in the superconducting properties of Nd-Ba-Cu-O/Ag large grains fabricated by a top-seeded melt growth process in controlled partial O pressures of 0.01 atm and 0.001 atm. Results of magnetic measurements show that Tc and critical current vary with position in a large sample. Such spatial variation in magnetic properties can be reduced when a sample is grown under a low O partial pressure. Trapped field distributions of Nd-Ba-Cu-O/Ag large grains reflect their spatial variations in the magnetic properties. In order to enhance the trapped field, it is necessary to optimize the local magnetic properties in the vicinity of the central axis in large-grain materials. 41 refs.