Weak Link Properties in QMG-Processed Superconducting Y-Ba-Cu-O

Abstract

In order to investigate the macroscopic properties of weak links in a QMG-processed Y-Ba-Cu-O specimen, the temperature dependence and the magnetic field history dependence of the critical current density and the critical current density under a longitudinal magnetic field were measured. The history effect was observed simultaneously at low temperatures where the critical current density initially decreased sharply with increasing temperature. On the other hand, the longitudinal field effect was observed up to a medium temperature at which the critical current density shows the second rapid fall. Above this temperature region, the temperature dependence of the critical current density approached the common one determined by the flux pinning mechanism, suggesting that the transport current only through strongly bounded region. It is considered from the observed results that two kinds of weak links exist in the present specimen.