Resolving the origin of pseudo-single domain magnetic behavior

Roberts, A. P., Almeida, T. P. , Church, N. S., Harrison, R. J., Heslop, D., Li, Y., Li, J., Muxworthy, A. R., Williams, W. and Zhao, X. (2017) Resolving the origin of pseudo-single domain magnetic behavior. Journal of Geophysical Research: Solid Earth, 122(12), pp. 9534-9558. (doi:10.1002/2017JB014860)

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Abstract

The term ‘pseudo-single domain’ (PSD) has been used to describe the transitional state in rock magnetism that spans the particle size range between the single domain (SD) and multi-domain (MD) states. The particle size range for the stable SD state in the most commonly occurring terrestrial magnetic mineral, magnetite, is so narrow (~20-75 nm) that it is widely considered that much of the paleomagnetic record of interest is carried by ‘PSD’ rather than stable SD particles. The PSD concept has, thus, become the dominant explanation for the magnetization associated with a major fraction of particles that record paleomagnetic signals throughout geological time. In this paper, we argue that in contrast to the SD and MD states, the term ‘PSD’ does not describe the relevant physical processes, which have been documented extensively using three-dimensional micromagnetic modeling, and by parallel research in materials science and solid-state physics. We also argue that features attributed to ‘PSD’ behavior can be explained by nucleation of a single magnetic vortex immediately above the maximum stable SD transition size. With increasing particle size, multiple vortices, antivortices, and domain walls can nucleate, which produce variable cancellation of magnetic moments and a gradual transition into the MD state. Thus, while the term ‘PSD’ describes a well-known transitional state, it fails to describe adequately the physics of the relevant processes. We recommend that use of this term should be discontinued in favor of “vortex state”, which spans a range of behaviors associated with magnetic vortices.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Almeida, Dr Trevor
Authors: Roberts, A. P., Almeida, T. P., Church, N. S., Harrison, R. J., Heslop, D., Li, Y., Li, J., Muxworthy, A. R., Williams, W., and Zhao, X.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Journal of Geophysical Research: Solid Earth
Publisher:Wiley
ISSN:2169-9313
ISSN (Online):2169-9313
Published Online:12 November 2017
Copyright Holders:Copyright © 2017 American Geophysical Union
First Published:First published in Journal of Geophysical Research: Solid Earth 122(12):9534-9558
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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