AC susceptibility measurement for Nd–Ba–Cu–O superconductor

Abstract Nd–Ba–Cu–O sample fabricated by the oxygen-controlled-melt-growth method exhibits large J c values in a high field region and also shows a secondary peak effect. In the present study, the Nd–Ba–Cu–O sample was characterized by using the flux profile technique, in which the χ ′ signal is plotted against the amplitude of AC field. J c values determined with the flux profile technique also showed a clear secondary peak effect. In addition, such J c values were higher than those measured with DC susceptibility, presumably due to a difference in the electric field to determine J c .