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Stability of Equidimensional Pseudo-Single Domain Magnetite Over Billion Year Time-Scales.

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Title: Stability of Equidimensional Pseudo-Single Domain Magnetite Over Billion Year Time-Scales.
Authors: Nagy, L
Williams, W
Muxworthy, AR
Fabian, K
Almeida, TP
Ó Conbhuí, P
Shcherbakov, V
Item Type: Journal Article
Abstract: Interpretations of paleomagnetic observations assume that naturally occurring magnetic particles can retain their primary magnetic recording over billions of years. The ability to retain a magnetic recording is inferred from laboratory measurements, where heating causes demagnetization on the order of seconds. The theoretical basis for this inference comes from previous models that assume only the existence of small, uniformly magnetized particles, whereas the carriers of paleomagnetic signals in rocks are usually larger, nonuniformly magnetized particles, for which there is no empirically complete, thermally activated model. This study has developed a thermally activated numerical micromagnetic model that can quantitatively determine the energy barriers between stable states in nonuniform magnetic particles on geological timescales. We examine in detail the thermal stability characteristics of equidimensional cuboctahedral magnetite and find that, contrary to previously published theories, such nonuniformly magnetized particles provide greater magnetic stability than their uniformly magnetized counterparts. Hence, nonuniformly magnetized grains, which are commonly the main remanence carrier in meteorites and rocks, can record and retain high-fidelity magnetic recordings over billions of years.
Issue Date: 5-Sep-2017
Date of Acceptance: 22-Jun-2017
URI: http://hdl.handle.net/10044/1/51629
DOI: https://dx.doi.org/10.1073/pnas.1708344114
ISSN: 1091-6490
Publisher: National Academy of Sciences
Start Page: 10356
End Page: 10360
Journal / Book Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 114
Issue: 39
Copyright Statement: © the authors
Sponsor/Funder: Natural Environment Research Council (NERC)
Funder's Grant Number: NE/J020508/1
Keywords: geomagnetism
micromagnetics
paleomagnetism
thermal stability
thermoremanence
MD Multidisciplinary
Publication Status: Published
Appears in Collections:Faculty of Engineering
Earth Science and Engineering



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