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Magnetic properties of feroxyhyte (δ-FeOOH) |
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| Authors: | C Bender Koch C A Oxborrow S Mørup M B Madsen A J Quinn J M D Coey |
| Institution: | 1. Physics Department, Technical University of Denmark, DK-2800, Lyngby, Denmark 2. Niels Bohr Institute for Astronomy, Physics, and Geophysics, ?rsted Laboratory, DK-2100, Copenhagen ?, Denmark 3. Department of Pure and Applied Physics, Trinity College, 2, Dublin, Ireland |
| Abstract: | Magnetization curves and high-field Mössbauer spectra are used to deduce a model for the magnetic order in synthetic samples of δ-FeOOH (feroxyhyte), which takes account of the changes in magnetization when the samples are heated at 105 °C. Feroxyhyte is essentially a planar antiferromagnet with the net sublattice moments aligned parallel or antiparallel to c. Each particle acquires a net moment due to the very small number of layers along the c-direction, and the presence of surface steps causing the formation of ferrimagnetic domains with an odd number of layers. There is some spin canting which is related to the crystallinity of the sample. The decrease in magnetization following heating is mainly due to an increase in the extent of antiferromagnetic coupling between the closely packed ferrimagnetic particles, but changes in the spin canting within the bulk may also contribute. A typical, rather well crystallized specimen has magnetization σ=14 JT?1 kg?1 and Curie temperature T c=455 K. |
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