American Physical Society
Tunneling measurements have been performed on both sides of the insulator-superconductor transition in quench-condensed granular Pb films. The results indicate that the Pb film consists of fully superconducting grains with essentially bulk values for the superconducting energy gap and transition temperature, even when the film exhibits insulating behavior in transport measurements. The density of states inferred from measurements in perpendicular magnetic field are consistent with magnetic spin-flip broadening.
R. P. Barber, Jr., L. M. Merchant, A. La Porta, and R. C. Dynes, "Tunneling into granular Pb films in the superconducting and insulating regimes," Physical Review B, 49, 3409, (1994).