Observing thermomagnetic stability of nonideal magnetite particles: good paleomagnetic recorders?

Almeida, T. P. , Kasama, T., Muxworthy, A. R., Williams, W., Nagy, L. and Dunin-Borkowski, R. E. (2014) Observing thermomagnetic stability of nonideal magnetite particles: good paleomagnetic recorders? Geophysical Research Letters, 41(20), pp. 7041-7047. (doi: 10.1002/2014GL061432)

Abstract

The thermomagnetic behavior of remanence-induced magnetite (Fe3O4) particles in the pseudo-single-domain (PSD) size range (~0.1–10 µm), which dominate the magnetic signature of many rock lithologies, is investigated using off-axis electron holography. Construction of magnetic induction maps allowed for the visualization of the vortex domain state in an individual Fe3O4 grain (~200 nm in diameter) as a function of temperature. Acquisition of a series of electron holograms at 100°C intervals during in situ heating up to 700°C demonstrates the vortex state of the Fe3O4 grain, in this instance, remains thermally stable close to its unblocking temperature and exhibits a similar in-plane remanent state upon cooling; i.e., the particle is effectively behaving like a uniaxial single-domain particle to temperatures near TC. Such particles are thought to be robust magnetic recorders. It is suggested that evidence for PSD behavior should therefore not preclude paleomagnetic investigation.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Almeida, Dr Trevor
• Authors: Almeida, T. P., Kasama, T., Muxworthy, A. R., Williams, W., Nagy, L., and Dunin-Borkowski, R. E.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Geophysical Research Letters
• Publisher: Wiley-Blackwell Publishing, Inc.
• ISSN: 0094-8276
• ISSN (Online): 1944-8007
• Copyright Holders: Copyright © 2014 American Geophysical Union
• First Published: First published in Geophysical Research Letters 41(20):7041-7047
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher