Evolution of spin relaxation processes in LiY1-xHoxF4 studied via ac-susceptibility and muon spin relaxation

Johnson, R. C., Malkin, B. Z., Lord, J. S., Giblin, Sean ORCID: https://orcid.org/0000-0003-1876-8619, Amato, A., Baines, C., Lascialfari, A., Barbara, B. and Graf, M. J. 2012. Evolution of spin relaxation processes in LiY1-xHoxF4 studied via ac-susceptibility and muon spin relaxation. Physical Review B Condensed Matter and Materials Physics 86 (1) , 014427. 10.1103/PhysRevB.86.014427

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Abstract

We present measurements of magnetic field and frequency dependence of the low-temperature (T = 1.8 K) ac-susceptibility and temperature and field dependence of the longitudinal field positive muon spin relaxation (μSR) for LiY1-xHoxF4 with x = 0.0017, 0.0085, 0.0408, and 0.0855. The fits of numerical simulations to the susceptibility data for the x = 0.0017, 0.0085, and 0.0408 show that Ho-Ho cross-relaxation processes become more important at higher concentrations, signaling the crossover from single-ion to correlated behavior. We simulate the muon spin depolarization using the parameters extracted from the susceptibility, and the simulations agree well with our data for samples with x = 0.0017 and 0.0085. The μSR data for samples with x = 0.0408 and 0.0855 at low temperatures (T < 10 K) cannot be described within a single-ion picture of magnetic field fluctuations and give evidence for additional mechanisms of depolarization due to Ho3+ correlations. We also observe an unusual peak in the magnetic field dependence of the muon relaxation rate in the temperature interval 10-20 K that we ascribe to a modification of the Ho3+ fluctuation rate due to a field induced shift of the energy gap between the ground and the first excited doublet crystal field states relative to a peak in the phonon density of states centered near 63 cm-1.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Spin glasses and other random magnets, Muon spin rotation and relaxation, Dynamic properties, Rare-earth ions and impurities
Publisher:	American Physical Society
ISSN:	1098-0121
Last Modified:	21 Oct 2022 10:51
URI:	https://orca.cardiff.ac.uk/id/eprint/41522

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