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Magnetic domain structure of multidomain magnetite as a function of temperature: observation by Kerr microscopy,

Ambatiello, A., K. Fabian, and V. Hoffmann (1999), Magnetic domain structure of multidomain magnetite as a function of temperature: observation by Kerr microscopy,, Physics of the Earth and Planetary Interiors, 112(1-2), 55-80.

Abstract
This study presents magnetic domain observations of the crystallographic (110)- and (Ill)-planes of various monocrystalline multidomain (MD) magnetites (Fe3O4) using the magneto-optical Kerr effect (MOKE). At room temperature (RT), lamellar domains separated by 180 degrees-, and closure domains with 71 degrees-, and 109 degrees-walls have been observed on the (110)-plane due to the two easy directions of magnetization within this plane. Domain structure observations on the (Ill)-plane reveal more complex domain patterns, which are formed by arrays of closure domains. Furthermore, in this study, the behaviour of the domain structure as a function of temperature has been observed. For high temperature domain observations, a special furnace has been developed which allows domain observations using the MOKE between room temperature and Curie-point (575 degrees C). During observation, the furnace is evacuated to 10(-3) Pa in order to prevent chemical alteration effects of the sample. The temperature dependence of the domain structure on the (110)-plane has been observed for various (MD) magnetites from Minais Gerais (Brazil) and the Zillertal (Austria). Magneto-optical domain contrasts could be observed up to 555 degrees C. During heating and cooling, the domain structure proved to be reversible. The mean domain width at each temperature step was determined by two methods in order to obtain an improved approximation. At RT, the mean domain width for different crystals varies between 40 and 90 mu m. The heating experiments on Brazilian magnetites show that the mean domain width is relatively stable from RT up to 350-400 degrees C; it then increases significantly at higher temperatures up to the Curie-point of magnetite. The experimental results are in good agreement with theoretical calculations of the absolute domain width in MD magnetite for a large range of grain sizes and varying temperatures. (C) 1999 Elsevier Science B.V. All rights reserved.
BibTeX
@article{id204,
  author = {A. Ambatiello and K. Fabian and V. Hoffmann},
  journal = {Physics of the Earth and Planetary Interiors},
  number = {1-2},
  pages = {55-80},
  title = {{Magnetic domain structure of multidomain magnetite as a function of temperature: observation by Kerr microscopy,}},
  volume = { 112},
  year = {1999},
  language = {en},
}
EndNote
%0 Journal Article
%A Ambatiello, A.
%A Fabian, K.
%A Hoffmann, V.
%D 1999
%N 1-2
%V  112
%J Physics of the Earth and Planetary Interiors
%P 55-80
%T Magnetic domain structure of multidomain magnetite as a function of temperature: observation by Kerr microscopy,
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