title: Extended van Hove singularity and superconducting instability in doped graphene.
abstract: We have investigated the effects of doping on a single layer of graphene using angle-resolved photoemission spectroscopy. We show that many-body interactions severely warp the Fermi surface, leading to an extended van Hove singularity (EVHS) at the graphene M point. The ground state properties of graphene with such an EVHS are calculated, analyzing the competition between a magnetic instability and the tendency towards superconductivity. We find that the latter plays the dominant role as it is enhanced by the strong modulation of the interaction along the Fermi line, leading to an energy scale for the onset of the pairing instability as large as 1 meV when the Fermi energy is sufficiently close to the EVHS.
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: McChesney
authors.forename: Aaron
authors.initials: A
authors.lastname: Bostwick
authors.forename: Taisuke
authors.initials: T
authors.lastname: Ohta
authors.forename: Thomas
authors.initials: T
authors.lastname: Seyller
authors.forename: Karsten
authors.initials: K
authors.lastname: Horn
authors.forename: J
authors.initials: J
authors.lastname: González
authors.forename: Eli
authors.initials: E
authors.lastname: Rotenberg