Origin of conductance asymmetry in the Andreev reflection spectra between normal metals and Fe-As based superconductors

ORAL

Abstract

Large conductance asymmetry is ubiquitously observed in point-contact Andreev reflection spectra between Fe-As based superconductors and metallic tips. We investigated the origin of this in point contacts between high quality epitaxial thin films of BaFe$_{1.84}$Co$_{0.16}$As$_{2}$ and sharp silver tips. In our experiments a large conductance asymmetry has been consistently observed in all the PCAR spectra. We discuss the possible origin of this conductance asymmetry.

*This research was supported by the Department of Energy through grant number DE-FG-02-06ER46346.

–

Authors

  • Manan Mehta

    • Department of Physics and Astronomy, Northwestern University

  • Goutam Sheet

    • Department of Physics and Astronomy, Northwestern University

  • D. Dikin

    • Department of Physics and Astronomy, Northwestern University

  • S. Lee

    • Department of Materials Science and Engineering, University of Wisconsin-Madison

  • J. Jiang

    • National High Magnetic Field Lab, Florida State Univeristy

  • C.W. Bark

    • Department of Materials Science and Engineering, University of Wisconsin-Madison

  • J.D. Weiss

    • National High Magnetic Field Lab, Florida State Univeristy

  • E.E. Hellstrom

    • National High Magnetic Field Lab, Florida State Univeristy

  • D.C. Larbalestier

    • National High Magnetic Field Lab, Florida State Univeristy

  • M.S. Rzchowski

    • Department of Physics, University of Wisconsin-Madison

  • C.B. Eom

    • Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Venkat Chandrasekhar

    • Department of Physics and Astronomy, Northwestern University