title: Superconducting graphene sheets in CaC6 enabled by phonon-mediated interband interactions.
abstract: There is a great deal of fundamental and practical interest in the possibility of inducing superconductivity in a monolayer of graphene. But while bulk graphite can be made to superconduct when certain metal atoms are intercalated between its graphene sheets, the same has not been achieved in a single layer. Moreover, there is a considerable debate about the precise mechanism of superconductivity in intercalated graphite. Here we report angle-resolved photoelectron spectroscopy measurements of the superconducting graphite intercalation compound CaC6 that distinctly resolve both its intercalant-derived interlayer band and its graphene-derived π* band. Our results indicate the opening of a superconducting gap in the π* band and reveal a substantial contribution to the total electron-phonon-coupling strength from the π*-interlayer interband interaction. Combined with theoretical predictions, these results provide a complete account for the superconducting mechanism in graphite intercalation compounds and lend support to the idea of realizing superconducting graphene by creating an adatom superlattice.
authors.affiliation: 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2] Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: S-L
authors.initials: SL
authors.lastname: Yang
authors.affiliation: 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2] Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Sobota
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
authors.forename: C A
authors.initials: CA
authors.lastname: Howard
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Pickard
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hashimoto
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Lu
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: S-K
authors.initials: SK
authors.lastname: Mo
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Kirchmann
authors.affiliation: 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2] Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen
mesh_terms: D004553:Electric Conductivity; D004583:Electrons; D006108:Graphite / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D060739:Phonons; D056951:Photoelectron Spectroscopy / Q000379:methods
chemical_list: D006108:Graphite