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Direct visualization of the thermomagnetic behavior of pseudo-single-domain magnetite particles

Almeida, Trevor P.; Muxworthy, Adrian R.; Kovacs, Andras; Williams, Wyn; Brown, Paul D.; Dunin-Borkowski, Rafal E.

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Authors

Trevor P. Almeida

Adrian R. Muxworthy

Andras Kovacs

Wyn Williams

Paul D. Brown

Rafal E. Dunin-Borkowski



Abstract

The study of the paleomagnetic signal recorded by rocks allows scientists to understand Earth’s past magnetic field and the formation of the geodynamo. The magnetic recording fidelity of this signal is dependent on the magnetic domain state it adopts. The most prevalent example found in nature is the pseudo–single-domain (PSD) structure, yet its recording fidelity is poorly understood. Here, the thermoremanent behavior of PSD magnetite (Fe3O4) particles, which dominate the magnetic signatures of many rock lithologies, is investigated using electron holography. This study provides spatially resolved magnetic information from individual Fe3O4 grains as a function of temperature, which has been previously inaccessible. A small exemplar Fe3O4 grain (~150 nm) exhibits dynamic movement of its magnetic vortex structure above 400°C, recovering its original state upon cooling, whereas a larger exemplar Fe3O4 grain (~250 nm) is shown to retain its vortex state on heating to 550°C, close to the Curie temperature of 580°C. Hence, we demonstrate that Fe3O4 grains containing vortex structures are indeed reliable recorders of paleodirectional and paleointensity information, and the presence of PSD magnetic signals does not preclude the successful recovery of paleomagnetic signals.

Citation

Almeida, T. P., Muxworthy, A. R., Kovacs, A., Williams, W., Brown, P. D., & Dunin-Borkowski, R. E. (2016). Direct visualization of the thermomagnetic behavior of pseudo-single-domain magnetite particles. Science Advances, 2(4), Article e1501801. https://doi.org/10.1126/sciadv.1501801

Journal Article Type Article
Acceptance Date Mar 23, 2016
Publication Date Apr 15, 2016
Deposit Date Jun 20, 2016
Publicly Available Date Jun 20, 2016
Journal Science Advances
Electronic ISSN 2375-2548
Publisher American Association for the Advancement of Science
Peer Reviewed Peer Reviewed
Volume 2
Issue 4
Article Number e1501801
DOI https://doi.org/10.1126/sciadv.1501801
Keywords Palaeomagnetism, magnetite, nanoparticles, in situ transmission electron microscopy, off-axis electron holography, pseudo–single-domain states, thermo-remanent magnetisation, thermomagnetic behavior
Public URL https://nottingham-repository.worktribe.com/output/784943
Publisher URL http://advances.sciencemag.org/content/2/4/e1501801
Related Public URLs http://advances.sciencemag.org/cgi/content/full/2/4/e1501801/DC1
Contract Date Jun 20, 2016

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