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Thursday, July 29, 2010

Superconducting Graphene

Extended van Hove Singularity and Superconducting Instability in Doped Graphene

J. L. McChesney, Aaron Bostwick, Taisuke Ohta, Thomas Seyller, Karsten Horn, J. González, and Eli Rotenberg

Phys. Rev. Lett. 104, 136803 (Published April 2, 2010)

Illustration: McChesney et al., Phys. Rev. Lett. (2010)

J. L. McChesney1,2, Aaron Bostwick1, Taisuke Ohta1,3, Thomas Seyller4, Karsten Horn3, J. González5, and Eli Rotenberg1
1Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
2Montana State University, Bozeman, Montana, USA
3Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
4Institut für Physik der Kondensierten Materie, Universität Erlangen-Nürnberg, Erlangen, Germany
5Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain

Received 18 November 2009; published 2 April 2010

See accompanying Physics Synopsis

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.

© 2010 The American Physical Society

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