Dynamic magnetic ground state in the dimer based compound Yb2⁢Te5⁢O13

We report the discovery of a dynamic magnetic ground state in the Yb3+ dimer-based compound Yb2⁢Te5⁢O13 through various characterization techniques down to sub-Kelvin temperatures. Magnetization measurements reveal the absence of long-range magnetic ordering down to 0.4 K and the onset of magnetic correlations below 1 K. Heat capacity data, measured down to 0.37 K, indicate a small finite energy gap in zero field, Δ⁡(0)∼ 0.55 K, and validate the presence of magnetic correlations with a Kramers doublet ground state (𝐽eff = 1/2). Further insight is provided by zero-field muon spin relaxation (𝜇⁢SR) measurements, which show a gradual slowdown of Yb3+ spin fluctuations below 30 K, indicating a dynamic state down to 44 mK. The temperature dependence of the relaxation rate, 𝜆, confirms the presence of the Orbach process, which is mediated through various crystal electric field levels, complementing the 𝐽eff = 1/2 ground state. Furthermore, longitudinal field 𝜇⁢SR measurements performed at 70 mK demonstrate that the Yb3+ spins remain dynamic even under an external field of 3200 Oe, with fluctuations becoming stronger with increasing magnetic field. Theoretical investigations further support the dynamic state, revealing competition between intra- and interdimer exchange interactions as the underlying cause. By integrating macroscopic and microscopic measurements with theoretical insights, we propose Yb2⁢Te5⁢O13 as a quantum spin liquid candidate, opening avenues for research in quantum magnetism.