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Scanning Tunneling Spectroscopy on the novel superconductor CaC6

N. Bergeal·V. Dubost·Y. Noat·W. Sacks·D. Roditchev·N. Emery·C. Herold·J-F. Mareche·P. Lagrange·G. Loupias
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Abstract

We present scanning tunneling microscopy and spectroscopy of the newly discovered superconductor CaC$_6$. The tunneling conductance spectra, measured between 3 K 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 $Δ(0)$ = 1.6 $\pm$ 0.2 meV. The possibility of gap anisotropy and two-gap superconductivity is also discussed. In a magnetic field, direct imaging of the vortices allows to deduce a coherence length in the ab plane $ξ_{ab}\simeq$ 33 nm.

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N. Bergeal, V. Dubost, Y. Noat, W. Sacks, D. Roditchev, N. Emery, C. Herold, J-F. Mareche, P. Lagrange, G. Loupias. 2006-04-07. Scanning Tunneling Spectroscopy on the novel superconductor CaC6. https://doi.org/10.1103/physrevlett.97.077003

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