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; M. Ellerby

doi:10.1103/PhysRevLett.102.107007

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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, M. Ellerby

DOI 10.1103/PhysRevLett.102.107007 · Physical Review Letters

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Abstract

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

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
CaC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	11.6	Pressure not reported	onset
YbC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown