Persistent superconductivity in ultrathin Pb films: A scanning tunneling spectroscopy study

Citation:
Eom, D, Qin S, Chou MY, Shih CK.  2006.  Persistent superconductivity in ultrathin Pb films: A scanning tunneling spectroscopy study, Jan. Physical Review Letters. 96:4., Number 2

Abstract:

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 (5-18 ML). The layer-dependent energy gap and transition temperature (T-c) show persistent quantum oscillations down to the lowest thickness without any sign of suppression. Moreover, by comparison with the quantum-well states measured above T-c and the theoretical calculations, we found that the T-c oscillation correlates directly with the density of states oscillation at E-F. 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.

Notes:

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