Non‐saturation of the defect moment of goethite and fine‐grained hematite up to 57 Teslas

DOI Web Site Web Site 被引用文献4件
  • Pierre Rochette
    CEREGE University of Aix‐Marseille 3 Aix en Provence France
  • Pierre‐Etienne Mathé
    CEREGE University of Aix‐Marseille 3 Aix en Provence France
  • Lionel Esteban
    Laboratoire des Mécanismes de Transferts en Géologie Université de Toulouse Toulouse France
  • Harison Rakoto
    Laboratoire National des Champs Magnétiques Pulsés Toulouse France
  • Jean‐Luc Bouchez
    Laboratoire des Mécanismes de Transferts en Géologie Université de Toulouse Toulouse France
  • Qingsong Liu
    Institute of Geophysics and Planetary Physics University of California Santa Cruz California USA
  • José Torrent
    Departamento de Ciencias y Recursos Agrícolas y Forestales Universidad de Córdoba Córdoba Spain

書誌事項

公開日
2005-11
権利情報
  • http://onlinelibrary.wiley.com/termsAndConditions#vor
DOI
  • 10.1029/2005gl024196
公開者
American Geophysical Union (AGU)

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説明

<jats:p>Defect moment of antiferromagnets yields the highest remanent coercivity observed among minerals, and previous studies have been unable to reach saturation of isothermal remanent magnetization (IRM) in some goethite and hematite, even up to 20 Teslas, using resistive Bitter magnets. To go further, acquisition of IRM at room temperature has been monitored on various natural and synthetic goethite and hematite samples in pulsed magnetic fields up to 57 Teslas. “Coarse” hematite is saturated around 5 T, and low unblocking temperature (T<jats:sub>B</jats:sub>, i.e. with low crystallinity or Al substitution) goethites saturate around 20 T. Higher T<jats:sub>B</jats:sub> goethites and a Mn‐bearing fine‐grained hematite are still not saturated even at 57 T, with only 2 to 10 percent of the maximum IRM acquired in 3 T. Half acquisition fields are mostly above 10 T. This indicates that usual rock magnetic techniques strongly underestimate the contribution of such minerals to remanence. IRM acquisition is strongly irreversible: in some samples a 57 T backfield is unable to erase a previous 38 T IRM. A field induced defect diffusion model is put forward to account for remanence acquisition in these materials.</jats:p>

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