Superconductivity-localization interplay and fluctuation magnetoresistance in epitaxial BaPb1−xBixO3 thin films

Doped BaBiO${}_{3}$ superconductors have for a long time attracted the interest of the condensed matter community due to the surprisingly high Tc, proximity to a charge-ordered phase, and similarities to the high-Tc cuprates in an isotropic, nonmagnetic system. In this work, the authors use the thickness of epitaxial BaPb${}_{1\ensuremath{-}x}$Bi${}_{x}$O${}_{3}$ films to drive a superconductor-insulator transition with disorder. Above Tc, magnetoresistance measurements show superconducting fluctuations that extend to remarkably high temperatures for the thickest films. These findings demonstrate both the important role of disorder in BaBiO${}_{3}$ superconductors, as well as the potential for this class of materials to serve as an important bridge between high-Tc cuprates and disordered conventional superconductors.