Two-Gap Superconductivity in 2H-NbS2

Abstract

We performed specific heat measurements of the superconducting single crystal of 2H-NbS2 in the temperature range down to 0.6 K and magnetic fields up to 14 T. The temperature and magnetic field dependence of the electronic specific heat consistently indicate existence of two superconducting energy gaps in the system. The superconducting anisotropy depends on both temperature and magnetic field. Moreover, the angular dependence of the upper critical field deviates from the Ginzburg-Landau behavior and rather reminds that of MgB2. All these features point to a multigap superconductivity in 2H-NbS2. Our measurements are in a perfect agreement with the previous scanning tunneling spectroscopy of Guillamon et al.