Electron-phonon Interaction in Graphite-Intercalation Compounds

After the discovery of superconductivity with a Tc of 11.5 K in Ca-intercalated graphite (CaC6 )[1], the interest in graphite-intercalation compounds has been revived. Different pairing mechanisms, based on excitons or electron-phonon interactions, have been put forward [2]. In this contribution we first analyze, using the NMTO[3] method, the electronic structure of CaC6. We then propose a simple model, based on pure graphite, to explain superconductivity in this class of compounds. Implications on the design of new materials with similar superconducting properties are also discussed. \newline [1] T.E. Weller {\em et al.}, Nature Physics {\bf 1}, 39 (2005). [2] G. Csany {\em et al.}, Nature Physics {\bf 1}, 42 (2005); I. I. Mazin, cond-mat/0504127; M. Calandra and F. Mauri, . [3] O.K. Andersen and T. Saha-Dasgupta, Phys. Rev. B 62, R16219 and O.K. Andersen, T. Saha-Dasgupta and S. Ezhov, Bull. Mat. Sci. 26, 19 (2003).