Direct observation of the thermal demagnetization of magnetic vortex structures in non-ideal magnetite recorders

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Title: Direct observation of the thermal demagnetization of magnetic vortex structures in non-ideal magnetite recorders
Authors: Almeida, TP
Muxworthy, AR
Kovacs, A
Williams, W
Nagy, L
Conbhuí, PC
Frandsen, C
Supakulopus, R
Dunin-Borkowski, RE
Item Type: Journal Article
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. Step-wise 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 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.
Issue Date: 19-Aug-2016
Date of Acceptance: 30-Jul-2016
ISSN: 1944-8007
Publisher: American Geophysical Union (AGU)
Start Page: 8426
End Page: 8434
Journal / Book Title: Geophysical Research Letters
Volume: 43
Issue: 16
Copyright Statement: ©2016. The Authors.This is an open access article under theterms of the Creative CommonsAttribution License, which permits use,distribution and reproduction in anymedium, provided the original work isproperly cited.
Sponsor/Funder: Natural Environment Research Council (NERC)
Funder's Grant Number: NE/J020508/1
Keywords: Meteorology & Atmospheric Sciences
MD Multidisciplinary
Publication Status: Published
Appears in Collections:Faculty of Engineering
Earth Science and Engineering

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