Unresolved problems in superconductivity of CaC6

Abstract

We discuss the current status of the theory of the "high-temperature" superconductivity in intercalated graphites YbC6 and CaC6. We emphasize that while the general picture of conventional, phonon-driven superconductivity has already emerged and is generally accepted, there are still interesting problems with this picture, such as weak-coupling regime inferred from specific heat suggesting coupling exclusively with high-energy carbon phonons coming in direct contradiction with the isotope effect measurements suggesting coupling exclusively with the low-energy intercalant modes. At the same time, the first principle calculations, while explaining Tc, contradict both of the experiments above by predicting equal coupling with both groups of phonons.

Contribution to the Proceedings of the M2S Conference in Dresden, 2006

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Cited by in corpus (16)

• Probing multiband superconductivity by point-contact spectroscopy
• Anisotropic Electron-Phonon Coupling and Dynamical Nesting on the Graphene Sheets in CaC6
• Electron-phonon interaction in Graphite Intercalation Compounds
• Electronic structure of superconducting KC${}_8$ and non-superconducting LiC${}_6$ graphite intercalation compounds: Evidence for a graphene-sheet-driven superconducting state
• Superconductivity in graphite intercalation compounds
• Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy
• Phononic Self energy effects and superconductivity in CaC${}_6$
• Raman response of Stage-1 graphite intercalation compounds revisited
• Evidence of Strong-Coupled Superconductivity in CaC6 from Tunneling Spectroscopy
• Phonons and superconductivity in YbC${}_6$ and related compounds
• Neutron scattering study of the high energy graphitic phonons in superconducting CaC${}_6$
• Raman scattering from the CaC6 superconductor in the presence of disorder
• Far-infrared signature of the superconducting gap in intercalated graphite CaC6
• Challenging the nature of low energy plasmon excitations in CaC${}_6$ using electron energy-loss spectroscopy
• Self-consistent theory of phonon renormalization and electron-phonon coupling near a 2D Kohn singularity
• Anisotropic superconductivity in graphite intercalation compound YbC6