Nanomagnetic properties of the meteorite cloudy zone

Einsle, J. F. , Eggeman, A. S., Martineau, B. H., Saghi, Z., Collins, S. M., Blukis, R., Bagot, P. A.J., Midgley, P. A. and Harrison, R. J. (2018) Nanomagnetic properties of the meteorite cloudy zone. Proceedings of the National Academy of Sciences of the United States of America, 115(49), E11436-E11445. (doi: 10.1073/pnas.1809378115) (PMID:30446616) (PMCID:PMC6298078)

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Abstract

Meteorites contain a record of their thermal and magnetic history, written in the intergrowths of iron-rich and nickel-rich phases that formed during slow cooling. Of intense interest from a magnetic perspective is the “cloudy zone,” a nanoscale intergrowth containing tetrataenite—a naturally occurring hard ferromagnetic mineral that has potential applications as a sustainable alternative to rare-earth permanent magnets. Here we use a combination of high-resolution electron diffraction, electron tomography, atom probe tomography (APT), and micromagnetic simulations to reveal the 3D architecture of the cloudy zone with subnanometer spatial resolution and model the mechanism of remanence acquisition during slow cooling on the meteorite parent body. Isolated islands of tetrataenite are embedded in a matrix of an ordered superstructure. The islands are arranged in clusters of three crystallographic variants, which control how magnetic information is encoded into the nanostructure. The cloudy zone acquires paleomagnetic remanence via a sequence of magnetic domain state transformations (vortex to two domain to single domain), driven by Fe–Ni ordering at 320 °C. Rather than remanence being recorded at different times at different positions throughout the cloudy zone, each subregion of the cloudy zone records a coherent snapshot of the magnetic field that was present at 320 °C. Only the coarse and intermediate regions of the cloudy zone are found to be suitable for paleomagnetic applications. The fine regions, on the other hand, have properties similar to those of rare-earth permanent magnets, providing potential routes to synthetic tetrataenite-based magnetic materials.

Item Type:Articles
Additional Information:J.F.E., P.A.M. and R.J.H. acknowledge funding under ERC Advanced Grant 320750-Nanopaleomagnetism. S.M.C. and P.A.M. acknowledge funding under ERC Advanced Grant 291522-3DIMAGE. S.M.C. acknowledges the Henslow Research Fellowship and Girton College, Cambridge. A.S.E. and B.H.M. acknowledge financial support from the Royal Society.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Einsle, Dr Joshua Franz
Authors: Einsle, J. F., Eggeman, A. S., Martineau, B. H., Saghi, Z., Collins, S. M., Blukis, R., Bagot, P. A.J., Midgley, P. A., and Harrison, R. J.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
Journal Name:Proceedings of the National Academy of Sciences of the United States of America
Publisher:National Academy of Sciences
ISSN:0027-8424
ISSN (Online):1091-6490
Published Online:16 November 2018
Copyright Holders:Copyright © 2018 National Academy of Sciences
First Published:First published in Proceedings of the National Academy of Sciences of the United States of America 115(49):E11436-E11445
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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