Possible gapless spin liquid in the rare-earth kagome lattice magnet Tm3Sb3Zn2 O14

Abstract

© 2018 American Physical Society. We report the thermodynamic and muon spin relaxation (μSR) evidences for a possible gapless spin liquid in Tm3Sb3Zn2O14, with the rare-earth ions Tm3+ forming a two-dimensional kagomé lattice. We extract the magnetic specific heat of Tm3Sb3Zn2O14 by subtracting the phonon contribution of the nonmagnetic isostructural material La3Sb3Zn2O14 and obtain a clear linear-T temperature dependence of magnetic specific heat at low temperatures. No long-range magnetic order was observed down to 0.35 K in the heat capacity measurements, and no signature of spin freezing down to 50 mK was observed in A.C. susceptibility measurements. The absence of magnetic order is further confirmed by the μSR measurements down to 20 mK. We find that the spin-lattice relaxation time remains constant down to the lowest temperature. We point out that the physics in Tm3Sb3Zn2O14 is fundamentally different from the Cu-based herbertsmithite and propose spin liquid ground states with non-Kramers doublets on the kagomé lattice to account for the experimental results. However, we cannot rule out that these exotic properties are induced by the Tm/Zn site-mixing disorder in Tm3Sb3Zn2O14.