Observation of a reentrant superconducting resistive transition in granular Ba${\mathrm{Pb}}_{0.75}$${\mathrm{Bi}}_{0.25}$${\mathrm{O}}_3$ superconductor

A normal-superconducting-normal transition has been observed resistively in the granular Ba${\mathrm{Pb}}_{0.75}$ ${\mathrm{Bi}}_{0.25}$ ${\mathrm{O}}_3$ compound, while the compound remains diamagnetic to the lowest temperature investigated. This has been attributed to the decoupling of the superconducting grains at low temperature caused by the reduction of charge carriers in the grain barriers, in good agreement with the theory.