Evidence of spatially inhomogeneous pairing on the insulating side of a disorder-tuned superconductor-insulator transition

Measurements of transport properties of amorphous insulating Inx Oy thin films grown on SrTiO3 substrates have been interpreted as evidence of the presence of superconducting islands on the insulating side of a disorder-tuned superconductor-insulator transition. Although the films appear not to be granular, their behavior is similar to that observed in granular films. The results support theoretical models in which the destruction of superconductivity by disorder produces spatially inhomogeneous pairing with a spectral gap.