Multiband Superconductivity in the Chevrel Phases SnMo6S8 and PbMo6S8
Authors: A.P. Petrović, R. Lortz, G. Santi, C. Berthod, C. Dubois, M. Decroux, A. Demuer, A.B. Antunes, A. Paré, D. Salloum, P. Gougeon, M. Potel, Ø. Fischer
Published in: Physical Review Letters 106, 017003, 2011.
Sub-Kelvin scanning tunneling spectroscopy in the Chevrel phases SnMo6S8 and PbMo6S8 reveals two distinct superconducting gaps with Δ1=3 meV, Δ2~1.0 meV and Δ1=3.1 meV, Δ2~1.4 meV, respectively. The gap distribution is strongly anisotropic, with Δ2 predominantly seen when scanning across unit-cell steps on the (001) sample surface. The spectra are well fitted by an anisotropic two-band BCS s-wave gap function. Our spectroscopic data are confirmed by electronic heat capacity measurements, which also provide evidence for a twin-gap scenario.
