Anisotropic superconducting gap probed by ${}^{125}$Te NMR in noncentrosymmetric Sc${}_{6}M$Te${}_2$ ($M$ = Fe, Co)

The superconducting gap symmetry is investigated by ${}^{125}$Te NMR measurements on Sc${}_{6}M$Te${}_2$ ($M$ = Fe, Co) without spatial inversion symmetry. The spin susceptibility obtained from the Knight shift $K$ is suppressed below the superconducting transition temperature, while leaving a finite value down to the lowest temperature ($\simeq 0.4$ K). The nuclear spin-lattice relaxation rate $1\mathrm{/}{T}_1$ follows a power law against temperature $T$ without showing a coherence peak characteristic of the isotropic gap. The result implies a pairing admixture or a residual density of states under magnetic field. The normal metallic state has a Korringa scaling relation between $1\mathrm{/}{T}_{1}T$ and the Knight shift, reflecting a weak electron correlation.