Scanning Tunneling Spectroscopy on the Novel Superconductor CaC6

N. Bergeal (1) , Vincent Dubost (1) , Yves Noat (1) , W. Sacks (1) , D. Roditchev (1) , N. Emery (2) , C. Herold (2) , J.-F. Marêche (2) , P. Lagrange (2) , G. Loupias (3)

1 INSP - Institut des Nanosciences de Paris
2 LCSM - Laboratoire de chimie du solide minéral
3 IMPMC - Institut de minéralogie et de physique des milieux condensés

We present scanning tunneling microscopy and spectroscopy of the newly discovered superconductor CaC6. The tunneling conductance spectra, measured between 3 and 15 K, show a clear superconducting gap in the quasiparticle density of states. The gap function extracted from the spectra is in good agreement with the conventional BCS theory with Delta(0) ~ 1.6±0.2 meV. The possibility of gap anisotropy and twogap superconductivity is also discussed. In a magnetic field, direct imaging of the vortices allows us to deduce a coherence length in the ab plane Eab~=33 nm.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

N. Bergeal, Vincent Dubost, Yves Noat, W. Sacks, D. Roditchev, et al.. Scanning Tunneling Spectroscopy on the Novel Superconductor CaC6. Physical Review Letters, 2006, 97, pp.077003. ⟨10.1103/PhysRevLett.97.077003⟩. ⟨hal-00117124⟩