Church, Nathan and Feinberg, Joshua M. and Harrison, Richard J. (2011) Low-temperature domain wall pinning in titanomagnetite: Quantitative modeling of multidomain first-order reversal curve diagrams and AC susceptibility. G3 Geochemistry Geophysics Geosystems, 12. Q07Z27. ISSN 1525-2027 DOI https://doi.org/10.1029/2011GC003538
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Abstract
Domain wall pinning in titanomagnetite has been investigated at low temperatures using first-order reversal curve (FORC) diagrams, AC magnetic susceptibility, and Lorentz transmission electron microscopy. A discontinuous transition from a low-coercivity extrinsic pinning regime to a high-coercivity intrinsic pinning regime is evident in low-temperature FORC diagrams on cooling from 100 to 50 K. Intrinsic pinning is characterized by a “crescent moon” FORC distribution with narrow coercivity distribution centered on 10–20 mT. This crescent-shaped FORC distribution is reproduced using a modification of Néel's (1955) one-dimensional theory of domain wall pinning in a random field. The pinning transition coincides with a thermally activated relaxation process (activation energy 0.13 ± 0.01 eV), attributed to electron hopping. The relaxation and intrinsic pinning are explained as a magnetoelastic aftereffect caused by enhancement of magnetocrystalline anisotropy due to rearrangement and localization of Fe2+−Fe3+ cations within the domain walls. This study provides experimental verification that Néel's theory is an appropriate quantitative framework for the analysis of FORC diagrams in multidomain titanomagnetite and suggests a potential method for the quantitative unmixing of multidomain signals from FORC diagrams in rock and environmental magnetic studies.
Item Type: | Article |
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Uncontrolled Keywords: | 2011AREP; IA63; |
Subjects: | 03 - Mineral Sciences |
Divisions: | 03 - Mineral Sciences |
Journal or Publication Title: | G3 Geochemistry Geophysics Geosystems |
Volume: | 12 |
Page Range: | Q07Z27 |
Identification Number: | https://doi.org/10.1029/2011GC003538 |
Depositing User: | Sarah Humbert |
Date Deposited: | 21 Oct 2011 16:58 |
Last Modified: | 23 Jul 2013 10:02 |
URI: | http://eprints.esc.cam.ac.uk/id/eprint/2209 |
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