AVS 52nd International Symposium
    Surface Science Friday Sessions
       Session SS2-FrM

Paper SS2-FrM7
Persistent Superconductivity in Ultra-Thin Pb Films: A Scanning Tunneling Spectroscopy Study

Friday, November 4, 2005, 10:20 am, Room 203

Session: Electronic Structure of Surfaces
Presenter: D. Eom, The University of Texas at Austin
Authors: D. Eom, The University of Texas at Austin
S. Qin, The University of Texas at Austin
M.-Y. Chou, Georgia Tech
C.K. Shih, The University of Texas at Austin
Correspondent: Click to Email
We report a direct probe of the superconducting order parameter of superconducting crystalline Pb films in the ultra-thin regime (5 -18 ML) by using a home-built low temperature scanning tunneling microscopy/spectroscopy (STM/S). Surprisingly, we find that the 2D cooper pair condensates remain extremely robust down to the thinnest film (5ML) without any signature of the transition temperature (Tc) suppression. Moreover, we find that the quantum oscillations of order parameter are also very persistent in this regime and the oscillation correlates directly with the density of states (DOS) oscillation at the Fermi level. Finally a constant value of the ratio of energy gap to Tc close to that of the bulk was found, implying the same strong coupling nature for electron-phonon interaction. More detailed analysis of the interplay of quantum size effects and superconductivity will be reported.