Magnetic field dependence of the resistivity and susceptibility of the above-100-K Bi-Sr-Ca-Cu superconductor.

The magnetic field dependence of the resistivity and susceptibility of multiphase Bi-Sr-Ca-Cu-O compounds exhibiting transport and diamagnetic anomalies at \ensuremath{\simeq}115 and \ensuremath{\simeq}75 K are reported. The field dependence of the latter yields values of ${H}_{c1}$ and $d\frac{{H}_{c2}}{\mathrm{dT}}(T={T}_{c})$ very similar to those found for the $\mathrm{Y}(R){\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$ family of Cu perovskitelike superconductors. The field dependence of the above-100-K region strongly suggests that bulk superconductivity, as opposed to filamentary or fluctuation behavior, dominates at these temperatures.