Infoscience

Journal article

Reduction of the Superconducting Gap of Ultrathin Pb Islands Grown on Si(111)

The energy gap Delta of superconducting Pb islands grown on Si(111) was probed in situ between 5 and 60 monolayers by low-temperature scanning tunneling spectroscopy. Delta was found to decrease from its bulk value as a function of inverse island thickness. Corresponding T-c values, estimated using bulk gap-to-T-c ratio, are in quantitative agreement with ex situ magnetic susceptibility measurements, however, in strong contrast to previous scanning probe results. Layer-dependent ab initio density functional calculations for freestanding Pb films show that the electron-phonon coupling constant, determining T-c, decreases with diminishing film thickness.

Fulltext

Related material