title: Scanning Tunneling Spectroscopy of Proximity Superconductivity in Epitaxial Multilayer Graphene.
abstract: We report on spatial measurements of the superconducting proximity effect in epitaxial graphene induced by a graphene-superconductor interface. Superconducting aluminum films were grown on epitaxial multilayer graphene on SiC. The aluminum films were discontinuous with networks of trenches in the film morphology reaching down to exposed graphene terraces. Scanning tunneling spectra measured on the graphene terraces show a clear decay of the superconducting energy gap with increasing separation from the graphene-aluminum edges. The spectra were well described by Bardeen-Cooper-Schrieffer (BCS) theory. The decay length for the superconducting energy gap in graphene was determined to be greater than 400 nm. Deviations in the exponentially decaying energy gap were also observed on a much smaller length scale of tens of nanometers.
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Fabian D
authors.initials: FD
authors.lastname: Natterer
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA.
authors.forename: Jeonghoon
authors.initials: J
authors.lastname: Ha
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Department of Physics and Astronomy, Seoul National University, Seoul, 151-747, Korea.
authors.forename: Hongwoo
authors.initials: H
authors.lastname: Baek
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA.
authors.forename: Duming
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA.
authors.forename: William
authors.initials: W
authors.lastname: Cullen
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Nikolai B
authors.initials: NB
authors.lastname: Zhitenev
authors.affiliation: Department of Physics and Astronomy, Seoul National University, Seoul, 151-747, Korea.
authors.forename: Young
authors.initials: Y
authors.lastname: Kuk
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Stroscio