Low-temperature STM Measurements of Granular Pb films

ORAL

Abstract

Using low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS) we have investigated the electronic properties of granular Pb films grown on HOPG at low temperature. Films grown under these conditions form a two-dimensional array of disconnected grains with a similar distribution of sizes. Local spectroscopy measurements as a function of field and temperature reveal a grain size dependent competition between the repulsive electron-electron interaction and the attractive superconducting pairing interaction. Our results show the presence of an increased depletion of states around the Fermi energy for all grain sizes, with a complete suppression of the superconducting state below a critical grain size. We compare these results to those found on 9ML and 100ML continuous films also grown on HOPG, where the superconducting state completely dominates the electronic properties.

*Work at Temple University was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0004556.

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Authors

  • S.A. Moore

    • Department of Physics, Temple University, Philadelphia, PA 19122

  • J. Fedor

    • Department of Physics, Temple University, Philadelphia, PA 19122

  • J. Curtis

    • Department of Physics, Drexel University, Philadelphia, PA 19104

  • G. Karapetrov

    • Department of Physics, Drexel University, Philadelphia, PA 19104

  • I. Beloborodov

    • Department of Physics, California State University Northridge, Northridge, CA 91330

  • M. Iavarone

    • Department of Physics, Temple University, Philadelphia, PA 19122