Irreversibility and vortex glass-liquid transition fields of silver-sheathed Bi-2212 superconducting tapes

The scaling of current-voltage curves is investigated and the irreversibility field and the vortex glass-liquid transition field are obtained for two specimens of multilayered Bi-2212 superconducting tapes with different thicknesses of superconducting layer. The results were compared with the theoretical analysis using: the flux creep-flow model in which the distribution of flux pinning strength was taken into account. A good agreement was obtained, although the dependence of the irreversibility field on the thickness of superconducting layer was not obtained since the longitudinal Aux bundle size was still shelter than the thickness of superconducting layers, resulting in bulk pinning. This agreement shows that the present theoretical model describes correctly the phenomena associated with the motion of flux lines under the influence of flux pinning.