Superconducting properties of the noncentrosymmetric superconductor Re6Hf

We report synthesis and detailed characterization of the noncentrosymmetric superconductor Re6Hf using powder x-ray diffraction (XRD), magnetization, transport, and thermodynamic measurements. XRD confirmed the noncentrosymmetric, alpha-Mn cubic structure in Re6Hf with the cubic cell parameter a = 9.6850(3) angstrom. Resistivity, DC, and AC magnetization measurements confirmed the type-II superconductivity in Re6Hf with the transition temperature T-c(onset) similar to 5.96 K, having the lower critical field H-c1(0) 5.6 mT and upper critical field Hc(2)(0) 12.2 T. The electronic specific heat data fits well with the single-gap BCS model. The Sommerfeld coefficient (gamma) also shows linear relation with the magnetic field. All above results suggest s-wave superconductivity in Re6Hf.