Multi-Gap Superconductivity in Chevrel Phases

ORAL

Abstract

Sub-Kelvin scanning tunnelling spectroscopy (STS) in the quasi-3D Chevrel Phases PbMo$_6$S$_8$ and SnMo$_6$S$_8$ reveals two distinct superconducting gaps at $\sim$~3meV and $\sim$~1meV. The relative spectral contribution from each gap changes with the angle between tip and sample, implying a rather anisotropic Fermi surface. Complementary to our local probe studies, specific heat measurements confirm the strong coupling (2$\Delta$/$k_B$$T_c$~$\sim$~4.9) seen by STS in each material and provide further evidence for multi-gap superconductivity. Hexagonal vortex lattices have been imaged by STS for each compound, with vortex core spectroscopy indicating a pseudogap within the cores. No pseudogap is visible in normal-state spectra, suggesting that the gapped vortex cores may be a novel consequence of two-band superconductivity.

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Authors

  • Alexander Petrovic

    • DPMC-MaNEP, University of Geneva, Switzerland

  • Cedric Dubois

    • DPMC-MaNEP, University of Geneva, Switzerland

  • Gilles Santi

    • DPMC-MaNEP, University of Geneva, Switzerland

  • Christophe Berthod

    • DPMC-MaNEP, University of Geneva, Switzerland

  • Oystein Fischer

    • DPMC-MaNEP, University of Geneva, Switzerland

  • Rolf Lortz

    • Department of Physics, Hong Kong University of Science and Technology, Hong Kong

  • Albin Demuer

    • Grenoble High Magnetic Field Laboratory, CNRS Grenoble, France

  • Arlei Antunes

    • Grenoble High Magnetic Field Laboratory, CNRS Grenoble, France

  • Antoine Pare

    • Grenoble High Magnetic Field Laboratory, CNRS Grenoble, France

  • Diala Salloum

    • Department of Chemistry, University of Rennes, France

  • Patrick Gougeon

    • Department of Chemistry, University of Rennes, France

  • Michel Potel

    • Department of Chemistry, University of Rennes, France