Flux pinning and critical currents in melt processed YBaCuO superconductors

The authors report flux pinning behavior of melt processed YBaCuO containing Y₂BaCuO₅(211) inclusions. Although the size of the 211 inclusions is relatively large compared to the coherence length, they can work as pinning centers. The authors present the mechanism for pinning due to large normal precipitates. While large flux creep is observed in thin films exhibiting high J_c values, flux creep rate is very small in melt processed YBaCuO having a magnitude lower J_c values, which is understandable by considering that the pinning potential of large normal precipitates is much larger than that of small pinning centers and thereby the flux motion is less affected by thermal activation.