Inhomogeneous Superconductivity in BaPb1−xBixO3

Transport and magnetization measurements of single crystas of BaPb1−xBixO3, for Bi compositions spanning the superconducting phase diagram, show signatures of granular and inhomogeneous superconductivity, possibly associated with the nanoscale structural phase separation found for compositions around optimal doping. The material exhibits a field-tuned superconductor-to-insulator transition for Bi compositions 0.24≤x≤0.28. For optimally doped samples (x≈0.25), the magnetoresistance curves show scaling, suggesting some kind of critical behavior.