The In-doped topological crystalline insulator Sn1−xInxTe is a candidate for a topological superconductor, where a pseudo-spin-triplet state has been proposed. To clarify the spin symmetry of Sn1−xInxTe, we perform 125Te-nuclear magnetic resonance (NMR) measurements in polycrystalline samples with 0≤ x ≤0.15. The penetration depth calculated from the NMR line width is T independent below half the superconducting transition temperature (Tc) in polycrystalline Sn0.96In0.04Te, which indicates a fully opened superconducting gap. In this sample, the spin susceptibility measured by the spin Knight shift (Ks) at an external magnetic field of µ0H0 = 0.0872 T decreases below Tc, and Ks(T = 0)/Ks(T = Tc) reaches 0.36 ± 0.10, which is far below the limiting value 2/3 expected for a spin-triplet state for a cubic crystal structure. Our result indicates that polycrystalline Sn0.96In0.04Te is a spin-singlet superconductor.
|Publication status||Published - May 24 2017|
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