Study of the Ground State Properties of LiHoxY1-xF4 Using Muon Spin Relaxation

LiHo(x)Y(1-x)F4 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 ≈ 15 mK. Instead, below ≈300 mK 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.