Anomalous magnetic noise in an imperfectly flat landscape in the topological magnet Dy2Ti2O7.
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Authors
Samarakoon, Anjana M
Grigera, SA
Tennant, D Alan
Kirste, Alexander
Strehlow, Peter
Meissner, Michael
Jaubert, Ludovic
Moessner, Roderich
Publication Date
2022-02-01Journal Title
Proc Natl Acad Sci U S A
ISSN
0027-8424
Publisher
Proceedings of the National Academy of Sciences
Volume
119
Issue
5
Pages
e2117453119-e2117453119
Type
Article
This Version
VoR
Physical Medium
Print
Metadata
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Samarakoon, A. M., Grigera, S., Tennant, D. A., Kirste, A., Klemke, B., Strehlow, P., Meissner, M., et al. (2022). Anomalous magnetic noise in an imperfectly flat landscape in the topological magnet Dy2Ti2O7.. Proc Natl Acad Sci U S A, 119 (5), e2117453119-e2117453119. https://doi.org/10.1073/pnas.2117453119
Abstract
Noise generated by motion of charge and spin provides a unique window into materials at the atomic scale. From temperature of resistors to electrons breaking into fractional quasiparticles, "listening" to the noise spectrum is a powerful way to decode underlying dynamics. Here, we use ultrasensitive superconducting quantum interference device (SQUIDs) to probe the puzzling noise in a frustrated magnet, the spin-ice compound Dy2Ti2O7 (DTO), revealing cooperative and memory effects. DTO is a topological magnet in three dimensions-characterized by emergent magnetostatics and telltale fractionalized magnetic monopole quasiparticles-whose real-time dynamical properties have been an enigma from the very beginning. We show that DTO exhibits highly anomalous noise spectra, differing significantly from the expected Brownian noise of monopole random walks, in three qualitatively different regimes: equilibrium spin ice, a "frozen" regime extending to ultralow temperatures, and a high-temperature "anomalous" paramagnet. We present several distinct mechanisms that give rise to varied colored noise spectra. In addition, we identify the structure of the local spin-flip dynamics as a crucial ingredient for any modeling. Thus, the dynamics of spin ice reflects the interplay of local dynamics with emergent topological degrees of freedom and a frustration-generated imperfectly flat energy landscape, and as such, it points to intriguing cooperative and memory effects for a broad class of magnetic materials.
Keywords
constrained dynamics, frustrated magnets, glass physics, noise measurements, spin ice
Sponsorship
Engineering and Physical Sciences Research Council (EP/K028960/1)
Engineering and Physical Sciences Research Council (EP/M007065/1)
Engineering and Physical Sciences Research Council (EP/P034616/1)
EPSRC (EP/T028580/1)
Identifiers
External DOI: https://doi.org/10.1073/pnas.2117453119
This record's URL: https://www.repository.cam.ac.uk/handle/1810/334527
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
Licence URL: https://creativecommons.org/licenses/by-nc-nd/4.0/
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