Muon Spin Relaxation Study of Frustrated Tm_3Sb_3Mg_2O_14 with Kagomé Lattice

The structure and magnetic properties of rare-earth ions Tm^3+ Kagomé lattice Tm_3Sb_3Mg_2O_14 are studied by x-ray diffraction, magnetic susceptibility and muon spin relaxation (μSR) experiments. The existence of a small amount of Tm/Mg site-mixing disorder is revealed. DC magnetic susceptibility measurement shows that Tm^3+ magnetic moments are antiferromagnetically correlated with a negative Curie–Weiss temperature of -26.3 K. Neither long-range magnetic order nor spin-glass transition is observed by DC and AC magnetic susceptibility, and confirmed by μSR experiment down to 0.1 K. However, the emergence of short-range magnetic order is indicated by the zero-field μSR experiments, and the absence of spin dynamics at low temperatures is evidenced by the longitudinal-field μSR technique. Compared with the results of Tm_3Sb_3Zn_2O_14, another Tm-based Kagomé lattice with much more site-mixing disorder, the gapless spin liquid like behaviors in Tm_3Sb_3Zn_2O_14 can be induced by disorder effect. Samples with perfect geometrical frustration are in urgent demand to establish whether QSL exists in this kind of materials with rare-earth Kagomé lattice.