Scanning tunneling spectroscopy study of the proximity effect in a disordered two-dimensional metal
L. Serrier-Garcia, J. C. Cuevas, T. Cren, C. Brun, V. Cherkez, F. Debontridder, D. Fokin, F. S. Bergeret, and D. Roditchev
Accepted
The proximity effect between a superconductor and a highly diffusive two-dimensional metal was revealed in a Scanning Tunneling Spectroscopy experiment. The in-situ elaborated samples consisted of superconducting single crystalline Pb islands interconnected by a non-superconducting atomically thin disordered Pb wetting layer. In the vicinity of each superconducting island the wetting layer acquires specific tunneling characteristics which reflect the interplay between the proximity-induced superconductivity and the inherent electron correlations of this ultimate diffusive two-dimensional metal. The observed spatial evolution of the tunneling spectra was accounted for theoretically by combining the Usadel equations with the theory of dynamical Coulomb blockade; the relevant length and energy scales were extracted and found in agreement with available experimental data.