Coexistence of random singlets and disordered Kitaev spin liquid in H3LiIr2 O6

Abstract

We combine static magnetic susceptibility χ(T), muon-spin relaxation, and H1 nuclear magnetic resonance measurements to explore the spin dynamics in the disordered-induced quantum spin liquid candidate H3LiIr2O6. Inverse Laplace transform analysis of the H1 spin-lattice relaxation rate 1/T1 enables us to identify two characteristic temperatures Tg=110K and T∗=26K. Below Tg, a slower 1/T1slow component dictated by gapped excitations with a spin gap Δh=30-38K evolves distinctly from a faster 1/T1fast component pertaining to gapless excitations. Furthermore, we observe a sub-Curie divergent χ(T)?T-0.68, a power-law dependent 1/T1fast?T1.4, and a weakly activated 1/T1slow?exp(-Δl/kBT) (Δl=3-6K) below T∗=26K. All these features suggest the coexistence of a disordered spin-liquid state and spin singlets with spatially distributed gaps. © 2023 American Physical Society.