Stability of supercurrents in a BiSrCaCuO (Bi-2212) high- Tcsuperconductor with artificially created defects

Abstract

Recent results in a systematic study of the stability of supercurrents in Bi-2212 tapes with randomly oriented, highly splayed columnar defects are presented as a function of defect density. The defects were artificially created by fission fragments of bismuth nuclei, fissioned by irradiation with energetic protons (∼0.8 GeV). Significant enhancements in the persistent current density Jpare observed at all temperatures and fields. Also, a marked shift of the irreversibility line towards higher fields and temperatures improves considerably the capacity of the material for practical applications. Moreover, a significant decrease in the logarithmic decay rate S=dln (Jp) /dln(t) indicates a strong stabilization of the persistent currents. All features point to high effectiveness of this artificial pinning mechanism. However, the optimal proton fluence needs yet to be established.