MAGNETIC-RELAXATION IN A AG-SHEATHED HIGH-JC BI-PB-SR-CA-CU-O SUPERCONDUCTING TAPE

Abstract

The magnetic relaxation and magnetization curves were studied on the Ag-sheathed and highly c-axis oriented Bi-Pb-Sr-Ca-Cu-O tape with transport J(c) > 10(4) A/cm2 at 77 K. Zero-field-cooled (ZFC) in-field relaxation for applied field perpendicular to the sample a-b plane was investigated. It was found that the field-dependent relaxation rate had a maximum in the certain applied field at various temperatures. The applied field at this maximum was greater than H*, the first field for which currents flow through the entire volume of the sample in the Bean's critical state model. Pinning energies were estimated at the maximal relaxation rate in a series of temperatures.