Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders

Almeida, T. P. , Muxworthy, A. R., Kovács, A., Williams, W., Nagy, L., Conbhuí, P. Ó., Frandsen, C., Supakulopas, R. and Dunin-Borkowski, R. E. (2016) Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders. Geophysical Research Letters, 43(16), pp. 8426-8434. (doi:10.1002/2016GL070074)

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Abstract

The thermal demagnetization of pseudo-single-domain (PSD) magnetite (Fe3O4) particles, which govern the magnetic signal in many igneous rocks, is examined using off-axis electron holography. Visualization of a vortex structure held by an individual Fe3O4 particle (~250 nm in diameter) during in situ heating is achieved through the construction and examination of magnetic-induction maps. Stepwise demagnetization of the remanence-induced Fe3O4 particle upon heating to above the Curie temperature, performed in a similar fashion to bulk thermal demagnetization measurements, revealed that its vortex state remains stable under heating close to its unblocking temperature and is recovered upon cooling with the same or reversed vorticity. Hence, the PSD Fe3O4 particle exhibits thermomagnetic behavior comparable to a single-domain carrier, and thus, vortex states are considered reliable magnetic recorders for paleomagnetic investigations.

Item Type:Articles (Letter)
Additional Information:The work was funded by the UK Natural Environment Research Council (NERC grant NE/J020508/1) and the European Research Council (Advanced ERC grant 320832).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Almeida, Dr Trevor
Authors: Almeida, T. P., Muxworthy, A. R., Kovács, A., Williams, W., Nagy, L., Conbhuí, P. Ó., Frandsen, C., Supakulopas, R., and Dunin-Borkowski, R. E.
Subjects:Q Science > QC Physics
Q Science > QE Geology
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Group:Materials and Condensed Matter Physics Group
Journal Name:Geophysical Research Letters
Publisher:Wiley
ISSN:0094-8276
ISSN (Online):1944-8007
Published Online:30 July 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Geophysical Research Letters 43(16):8426-8434
Publisher Policy:Reproduced under a Creative Commons License

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