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arXiv · 2506.02484

Anisotropic superconducting gap probed by $^{125}$Te NMR in noncentrosymmetric Sc$_6M$Te$_2$ ($M$ = Fe, Co)

Kanako Doi·Hayase Takei·Yusaku Shinoda·Yoshihiko Okamoto·Daigorou Hirai·Koshi Takenaka·Taku Matsushita·Yoshiaki Kobayashi·Yasuhiro Shimizu
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Abstract

The superconducting gap symmetry is investigated by $^{125}$Te NMR measurements on Sc$_6M$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 $1/T_1$ 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 $1/T_1T$ and the Knight shift, reflecting a weak electron correlation.

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Kanako Doi, Hayase Takei, Yusaku Shinoda, Yoshihiko Okamoto, Daigorou Hirai, Koshi Takenaka, Taku Matsushita, Yoshiaki Kobayashi, Yasuhiro Shimizu. 2025-06-03. Anisotropic superconducting gap probed by $^{125}$Te NMR in noncentrosymmetric Sc$_6M$Te$_2$ ($M$ = Fe, Co). https://doi.org/10.1103/physrevb.111.214502

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