Study of the ground state properties of LiHoxY1-xF4 using muon spin relaxation

LiHoxY1-xF4 is an insulator where the magnetic Ho3⁺ ions have an Ising character and interact mainly through magnetic dipolar fields. We used the muon spin relaxation technique to study the nature of its ground state for samples with x≤0.25. In contrast with some previous works, we did not find canonical spin glass behavior down to ≈15mK. Instead, below ≈300mK we observed temperature-independent dynamic magnetism characterized by a single correlation time. The 300 mK energy scale corresponds to the Ho³⁺ hyperfine interaction strength, suggesting that this interaction may be involved in the dynamic behavior of the system.