Spin Ice: Magnetic Excitations without Monopole Signatures using Muon Spin Rotation

Theory predicts the low-temperature magnetic excitations in spin ices consist of deconfined magnetic charges, or monopoles. A recent transverse-field (TF) muon spin rotation (muSR) experiment [S T Bramwell et al, Nature 461, 956 (2009)] reports results claiming to be consistent with the temperature...

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Bibliographic Details
Published in:arXiv.org 2011-11
Main Authors: Dunsiger, S R, Aczel, A A, Arguello, C, Dabkowska, H, Dabkowski, A, M -H Du, Goko, T, Javanparast, B, Lin, T, Ning, F L, Noad, H M L, Singh, D J, Williams, T J, Uemura, Y J, Gingras, M J P, Luke, G M
Format: Article
Language:English
Subjects:
Electrons
Excitation
Magnetic materials
Magnetism
Monopoles
Muon spin rotation
Muons
Nucleation
Rotation
Spin ice
Temperature dependence
Variations
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Summary:Theory predicts the low-temperature magnetic excitations in spin ices consist of deconfined magnetic charges, or monopoles. A recent transverse-field (TF) muon spin rotation (muSR) experiment [S T Bramwell et al, Nature 461, 956 (2009)] reports results claiming to be consistent with the temperature and magnetic field dependence anticipated for monopole nucleation - the so-called second Wien effect. We demonstrate via a new series of muSR experiments in Dy_2Ti_2O_7 that such an effect is not observable in a TF muSR experiment. Rather, as found in many highly frustrated magnetic materials, we observe spin fluctuations which become temperature independent at low temperatures, behavior which dominates over any possible signature of thermally nucleated monopole excitations.
ISSN:2331-8422
DOI:10.48550/arxiv.1110.0877