Vortex phases and c-axis correlation in as-grown and heavy ion irradiated Bi₂Sr₂Ca₂Cu₃O_{10 +} tapes: a flux transformer experiment

We report transport measurements on as-grown and heavy ion irradiated tapes of (Bi-Pb)₂ Sr₂ Ca₂ Cu₃ O₁₀₊ (Bi-2223) superconductor performed using a flux transformer (FT) geometry. A two level resistive transition is identified. Our studies suggest the existence of three vortex liquid regimes with different c -axis correlation of the unirradiated tape. These observations are compared with reported FT measurements on YBa₂ Cu₃ O₇and Bi₂ Sr₂ CaCu₂ O₈superconductors. The system behaves like twinned YBCO due to the presence of growth related defects and misorientation between the crystallites Columnar defects (CDs) renormalize the inherent anisotropy of Bi-2223 further and a highly c -axis correlated vortex liquid is formed in samples with the CDs.