title: Visualized effect of oxidation on magnetic recording fidelity in pseudo-single-domain magnetite particles.
abstract: Magnetite (Fe3O4) is an important magnetic mineral to Earth scientists, as it carries the dominant magnetic signature in rocks, and the understanding of its magnetic recording fidelity provides a critical tool in the field of palaeomagnetism. However, reliable interpretation of the recording fidelity of Fe3O4 particles is greatly diminished over time by progressive oxidation to less magnetic iron oxides, such as maghemite (γ-Fe2O3), with consequent alteration of remanent magnetization potentially having important geological significance. Here we use the complementary techniques of environmental transmission electron microscopy and off-axis electron holography to induce and visualize the effects of oxidation on the magnetization of individual nanoscale Fe3O4 particles as they transform towards γ-Fe2O3. Magnetic induction maps demonstrate a change in both strength and direction of remanent magnetization within Fe3O4 particles in the size range dominant in rocks, confirming that oxidation can modify the original stored magnetic information.
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Trevor P
authors.initials: TP
authors.lastname: Almeida
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kasama
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Muxworthy
authors.affiliation: School of GeoSciences, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JW, UK.
authors.forename: Wyn
authors.initials: W
authors.lastname: Williams
authors.affiliation: School of GeoSciences, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JW, UK.
authors.forename: Lesleis
authors.initials: L
authors.lastname: Nagy
authors.affiliation: Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Hansen
authors.affiliation: Division of Materials, Mechanics and Structures, Department of Mechanical, Materials and Manufacturing Engineering, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich D-52425, Germany.
authors.forename: Rafal E
authors.initials: RE
authors.lastname: Dunin-Borkowski