Multidomain hematite: A source of planetary magnetic anomalies?

Citation
Dj. Dunlop et G. Kletetschka, Multidomain hematite: A source of planetary magnetic anomalies?, GEOPHYS R L, 28(17), 2001, pp. 3345-3348
Citations number
22
Categorie Soggetti
Earth Sciences
Journal title
GEOPHYSICAL RESEARCH LETTERS
ISSN journal
00948276 → ACNP
Volume
28
Issue
17
Year of publication
2001
Pages
3345 - 3348
Database
ISI
SICI code
0094-8276(20010901)28:17<3345:MHASOP>2.0.ZU;2-U
Abstract
Thermoremanent magnetization (TRM) in hematite is larger than TRM in magnet ite for grain sizes greater than or equal to 10 mum. 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 proport ional 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 (approximate to0.3 Am-2/kg) outweighs TRM and induced magnet ization of MD magnetite (approximate to0.01-0.02 Am-2/kg) and rivals TRM of single-domain and PSD magnetite as a source of magnetic anomalies on Earth and perhaps on Mars.