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Multidomain hematite: A source of planetary magnetic anomalies?
Author(s) -
Dunlop David J.,
Kletetschka Gunther
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013125
Subject(s) - hematite , magnetite , thermoremanent magnetization , magnetization , mars exploration program , condensed matter physics , demagnetizing field , geology , natural remanent magnetization , magnetic field , materials science , mineralogy , physics , astrobiology , remanence , paleontology , quantum mechanics
Thermoremanent magnetization (TRM) in hematite is larger than TRM in magnetite for grain sizes ≥10 µm. We show that hematite's weak spontaneous magnetization M s causes its strong TRM, since the self‐demagnetizing field H d opposing large domain wall displacements is proportional to M s . In hematite, H d is comparable to the Earth's magnetic field but in magnetite, H d is 1000 times larger. As a result, Earth's field TRM of MD hematite (≈ 0.3 Am²/kg) outweighs TRM and induced magnetization of MD magnetite (≈0.01–0.02 Am²/kg and rivals TRM of single‐domain and PSD magnetite as a source of magnetic anomalies on Earth and perhaps on Mars.