Anisotropic Electron-Phonon Coupling and Dynamical Nesting on the Graphene Sheets in Superconducting CaC6 using Angle-Resolved Photoemission Spectroscopy

T. Valla, J. Camacho, Z.-H. Pan, A. V. Fedorov, A. C. Walters, C. A. Howard, and M. Ellerby
Phys. Rev. Lett. 102, 107007 – Published 13 March 2009

Abstract

We present the first angle-resolved photoemission studies of electronic structure in CaC6, a superconducting graphite intercalation compound with Tc=11.6K. 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.

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  • Received 7 June 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.107007

©2009 American Physical Society

Authors & Affiliations

T. Valla1,*, J. Camacho1, Z.-H. Pan2, A. V. Fedorov2, A. C. Walters3, C. A. Howard3, and M. Ellerby3

  • 1Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
  • 2Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 3London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom

  • *valla@bnl.gov

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Vol. 102, Iss. 10 — 13 March 2009

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