Electronic Structure of Superconducting KC8 and Nonsuperconducting LiC6 Graphite Intercalation Compounds: Evidence for a Graphene-Sheet-Driven Superconducting State

Z.-H. Pan, J. Camacho, M. H. Upton, A. V. Fedorov, C. A. Howard, M. Ellerby, and T. Valla
Phys. Rev. Lett. 106, 187002 – Published 6 May 2011

Abstract

We have performed photoemission studies of the electronic structure in LiC6 and KC8, a nonsuperconducting and a superconducting graphite intercalation compound, respectively. We have found that the charge transfer from the intercalant layers to graphene layers is larger in KC8 than in LiC6, opposite of what might be expected from their chemical composition. We have also measured the strength of the electron-phonon interaction on the graphene-derived Fermi surface to carbon derived phonons in both materials and found that it follows a universal trend where the coupling strength and superconductivity monotonically increase with the filling of graphene π* states. This correlation suggests that both graphene-derived electrons and graphene-derived phonons are crucial for superconductivity in graphite intercalation compounds.

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  • Received 20 March 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.187002

© 2011 American Physical Society

Authors & Affiliations

Z.-H. Pan1, J. Camacho1, M. H. Upton2, A. V. Fedorov3, C. A. Howard4, M. Ellerby4, and T. Valla1,*

  • 1Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973, USA
  • 2Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60192, USA
  • 3Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 4London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom

  • *valla@bnl.gov

Comments & Replies

Comment on “Electronic Structure of Superconducting KC8 and Nonsuperconducting LiC6 Graphite Intercalation Compounds: Evidence for a Graphene-Sheet-Driven Superconducting State”

M. Calandra, C. Attaccalite, G. Profeta, and F. Mauri
Phys. Rev. Lett. 108, 149701 (2012)

Pan et al. Reply:

Z.-H. Pan, A. V. Fedorov, C. A. Howard, M. Ellerby, and T. Valla
Phys. Rev. Lett. 108, 149702 (2012)

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Vol. 106, Iss. 18 — 6 May 2011

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