Superconductivity in C6Ca

Matteo Calandra (1) , Francesco Mauri (1)

1 LMCP - Laboratoire de minéralogie, cristallographie de Paris

Using density functional theory we demonstrate that superconductivity in C6Ca is due to a phonon-mediated mechanism with electron-phonon coupling 0.83 and phonon-frequency logarithmic-average 24.7 meV. The calculated isotope exponents are 0.24 for Ca and 0.26 for C. Superconductivity is mostly due C vibrations perpendicular and Ca vibrations parallel to the graphite layers. Since the electron-phonon couplings of these modes are activated by the presence of an intercalant Fermi surface, the occurrence of superconductivity in graphite intercalated compounds requires a non complete ionization of the intercalant.

Domaines: Supraconductivité [cond-mat.supr-con]; Science des matériaux [cond-mat.mtrl-sci]

Matteo Calandra, Francesco Mauri. Superconductivity in C6Ca. Physical Review Letters, 2005, 95, pp.0506082. ⟨hal-00019057⟩