SrPt 2 As 2 undergoes a structural transition around 470 K (from a high-temperature tetragonal to a lowtemperature orthorhombic phase) accompanied by a charge density wave transition and followed by a superconducting transition at much lower temperature (5 K). The superconducting gap symmetry of this noncentrosymmetric compound was investigated in detail by means of muon-spin rotation or relaxation (μSR) experiments in transverse-field (TF) configuration. The temperature-dependent magnetic penetration depth obtained from the TF-μSR spectra suggests an isotropic s-wave-type superconducting gap. No observable differences are seen in the asymmetry time spectra collected in zero field above and below the superconducting transition temperature T c. This strongly suggests the absence of spontaneous magnetic fields in the superconducting state, hence pointing to a preserved time-reversal symmetry below T c .

We combine static magnetic susceptibility χ (T ), muon-spin relaxation, and 1 H nuclear magnetic resonance measurements to explore the spin dynamics in the disordered-induced quantum spin liquid candidate H 3 LiIr 2 O 6 . Inverse Laplace transform analysis of the 1 H spin-lattice relaxation rate 1/T 1 enables us to identify two characteristic temperatures T g = 110 K and T * = 26 K. Below T g , a slower 1/T slow 1 component dictated by gapped excitations with a spin gap h = 30-38 K evolves distinctly from a faster 1/T fast 1 component pertaining to gapless excitations. Furthermore, we observe a sub-Curie divergent χ (T ) ∝ T −0.68 , a power-law dependent 1/T fast 1 ∝ T 1.4 , and a weakly activated 1/T slow 1 ∝ exp(− l /k B T ) ( l = 3-6 K) below T * = 26 K. All these features suggest the coexistence of a disordered spin-liquid state and spin singlets with spatially distributed gaps.

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