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Nanoscale Imaging of High-Field Magnetic Hysteresis in Meteoritic Metal Using X-Ray Holography
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  • Roberts Blukis,
  • Bastian Pfau,
  • Christian Günther,
  • Piet Hessing,
  • Stefan Eisebitt,
  • Joshua Franz Einsle,
  • Richard Harrison
Roberts Blukis
GFZ German Research Centre for Geosciences

Corresponding Author:rblukis@gfz-potsdam.de

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Bastian Pfau
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Christian Günther
Technische Universität Berlin
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Piet Hessing
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Stefan Eisebitt
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Joshua Franz Einsle
School of Geographical and Earth Sciences
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Richard Harrison
University of Cambridge
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Stable paleomagnetic information in meteoritic metal is carried by the cloudy zone ~1-10 micron wide regions containing islands of ferromagnetic tetrataenite embedded in a paramagnetic antitaenite matrix. Due to their small size and high coercivity (~2.2 T), the tetrataenite islands carry very stable magnetic remanence. However, these characteristics also make it difficult to image their magnetic state with the necessary spatial resolution and applied magnetic field. Here we describe the first application of X-ray holography to image the magnetic structure of the cloudy zone of the Tazewell IIICD meteorite with spatial resolution down to ~40 nm and in applied magnetic fields up to 1.1 T, sufficient to extract high-field hysteresis data from individual islands. Images were acquired as a function of magnetic fields applied both parallel and perpendicular to the surface of a ~100 nm thick slice of the cloudy zone. Broad distributions of coercivity are observed, including values that likely exceed the maximum applied field. Horizontal offsets in the hysteresis loops indicate an interaction field distribution with half width of ~100 mT between the islands in their room-temperature single-domain state, providing a good match to first-order reversal curve diagrams. The role of interactions during the acquisition of transformation chemical remnant magnetization as the meteorite parent body is cooled, and the implications for extracting quantitative estimates of the paleofield, are discussed
Aug 2020Published in Geochemistry, Geophysics, Geosystems volume 21 issue 8. 10.1029/2020GC009044