A single full gap in noncentrosymmetric superconductor Re6Hf by point-contact spectroscopy

We report a point-contact spectroscopy study on the noncentrosymmetric superconductor Re6Hf with a superconducting transition temperature Tc ∼ 6.0 K. The point-contact conductance spectra can be well fitted by an s-wave Blonder-Tinkham-Klapwijk (BTK) model, where the superconducting gap follows a standard BCS behavior as a function of temperature or magnetic field. The gap at 0 K is estimated to be Δ0 ∼ 0.92 meV, yielding 2Δ0/kBTc ∼ 3.56. Hence, our results are consistent with a fully gaped s-wave pairing symmetry with a negligible spin-triplet superconducting component in Re6Hf.