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

Nd-Ba-Cu-O sample fabricated by the oxygen-controlled-melt-growth method ex hibits 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 chi ' signal is plotted a gainst the amplitude of AC field. J(c) values determined with the flux prof ile technique also showed a clear secondary peak effect. In addition, such J(c) values were higher than those measured with DC susceptibility, presuma bly due to a difference in the electric field to determine J(c). (C) 2001 P ublished by Elsevier Science B.V.