Diverging Characteristic Lengths at Critical Disorder in Thin-Film Superconductors

The characteristic lengths associated with the flux-flow resistance and with the critical fields measured at the vortex-antivortex transition temperature of thin-film In/InOₓ composites have been found to be approximately equal and to diverge simultaneously near critical disorder where superconductivity disappears. The observed disorder-induced enhancement of the vortex mobility cannot be explained by the dirty-limit formula for the coherence length when used within the context of the Bardeen-Stephen description for vortex dissipation.