Perpendicular upper critical field of granular Pb films near the superconductor-to-insulator transition

Shih-ying Hsu*, J. M. Valles

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

We have measured the perpendicular upper critical field, Hc2(T), in ultrathin granular Pb films with normal-state sheet resistances, RN, that range from 10 Ω to 11 kΩ. The films with the highest RN are near the threshold for the superconductor-to-insulator (S-I) transition. We compare our results to calculations for granular superconductors and obtain values for the grain size and coherence length characteristic of a single grain. In addition, we present a measurement of the ratio of the intergrain Josephson-coupling energy to the single-grain condensation energy near the S-I transition in these films. The small value of this ratio, 0.05, at RN=11 kΩ is consistent with the picture that fluctuations in the phase of the order parameter dominate the S-I transition in these films.

Original languageEnglish
Pages (from-to)14334-14337
Number of pages4
JournalPhysical Review B
Volume47
Issue number21
DOIs
StatePublished - 1993

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