Electronic structure of superconducting KC${}_8$ and non-superconducting LiC${}_6$ graphite intercalation compounds: Evidence for a graphene-sheet-driven superconducting state

Abstract

We have performed photoemission studies of the electronic structure in LiC${}_6$ and KC${}_8$, a non-superconducting and a superconducting graphite intercalation compound, respectively. We have found that the charge transfer from the intercalant layers to graphene layers is larger in KC${}_8$ than in LiC${}_6$, 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 ${\pi }^{\ast }$ states. This correlation suggests that both graphene-derived electrons and graphene-derived phonons are crucial for superconductivity in graphite intercalation compounds.

4 pages, 3 figures

References in corpus (6)

• Self-consistent self-energy analysis of photoemission data
• Bare electron dispersion from photoemission experiments
• Anisotropic Electron-Phonon Coupling and Dynamical Nesting on the Graphene Sheets in CaC6
• Specific Heat of the Ca-Intercalated Graphite Superconductor CaC${}_6$
• Unresolved problems in superconductivity of CaC6
• Effect of linear density of states on the quasi-particle dynamics and small electron-phonon coupling in graphite

Cited by in corpus (1)

• Non-conventional Superconductors and Percolation