Abstract
Magnetization measurements have been performed on Bi(Pb)2212 single crystals with various electromagnetic anisotropies before and after introducing columnar defects by Ta ion irradiation. The irreversibility fields of these crystals increased systematically with decreasing at various reduced temperatures indicating that the smaller anisotropy makes the columnar defects substantially more effective in flux pinning. The record-high irreversibility field and critical current density for single crystals of the Bi2212 phase was observed in our oxygen-overdoped Bi(Pb)2212 with columnar defects. This study experimentally reveals the reduction of the electromagnetic anisotropy and the introduction of pinning centers work cooperatively in high- superconductor compounds.
- Received 17 December 1999
DOI:https://doi.org/10.1103/PhysRevB.62.1452
©2000 American Physical Society