title: Anisotropic electron-phonon coupling and dynamical nesting on the graphene sheets in superconducting CaC6 using angle-resolved photoemission spectroscopy.
abstract: We present the first angle-resolved photoemission studies of electronic structure in CaC6, a superconducting graphite intercalation compound with T_{c}=11.6 K. We find that, contrary to theoretical models, the electron-phonon coupling on the graphene-derived Fermi sheets with high-frequency graphene-derived phonons is surprisingly strong and anisotropic. The shape of the Fermi surface is found to favor a dynamical intervalley nesting via exchange of high-frequency phonons. Our results suggest that graphene sheets play a crucial role in superconductivity in graphite intercalation compounds.
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA. valla@bnl.gov
authors.forename: T
authors.initials: T
authors.lastname: Valla
authors.forename: J
authors.initials: J
authors.lastname: Camacho
authors.forename: Z-H
authors.initials: ZH
authors.lastname: Pan
authors.forename: A V
authors.initials: AV
authors.lastname: Fedorov
authors.forename: A C
authors.initials: AC
authors.lastname: Walters
authors.forename: C A
authors.initials: CA
authors.lastname: Howard
authors.forename: M
authors.initials: M
authors.lastname: Ellerby