Persistent Superconductivity in Ultrathin Pb Films : A Scanning Tunneling Spectroscopy Study

Daejin EOM*, S. QIN, M.-Y. CHOU, C. K. SHIH

*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)peer-review

253 Citations (Scopus)


By using a low temperature scanning tunneling microscope we have probed the superconducting energy gap of epitaxially grown Pb films as a function of the layer thickness in an ultrathin regime (5-18ML). The layer-dependent energy gap and transition temperature (Tc) show persistent quantum oscillations down to the lowest thickness without any sign of suppression. Moreover, by comparison with the quantum-well states measured above Tc and the theoretical calculations, we found that the Tc oscillation correlates directly with the density of states oscillation at EF. The oscillation is manifested by the phase matching of the Fermi wavelength and the layer thickness, resulting in a bilayer periodicity modulated by a longer wavelength quantum beat. © 2006 The American Physical Society.
Original languageEnglish
Article number027005
JournalPhysical Review Letters
Issue number2
Early online date18 Jan 2006
Publication statusPublished - 20 Jan 2006
Externally publishedYes


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