Grain-size dependence of two-dimensional micromagnetic structures for pseudo-single-domain magnetite (0.2–2.5 μm) |
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| Authors: | Koji Fukuma & David J Dunlop |
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| Institution: | Department of Physics, Erindale College, University of Toronto, Mississauga, Ontario, Canada. E-mail: |
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| Abstract: | Micromagnetic modelling with a Monte Carlo method was performed to obtain 2-D micromagnetic structures of pseudo-single-domain (PSD) magnetite (0.2–2.5 μm). Cubic model grains were subdivided into a 2-D array with a maximum of 100×100 cells. In order to find an appropriate cell size, the variation of the self-consistency parameter ( S ) with cell size was examined. We regard solutions with S >0.95, which corresponds to cell sizes ≤0.03 μm, as representing realistic micromagnetic structures. For saturation remanence states, we found vortex structures for small PSD grains (≤0.25 μm) and closure domain structures for larger PSD grains (0.6–2.5 μm). Between 0.25 and 0.6 μm, structures remained chaotic even after a very large number of Monte Carlo steps. In grains with a closure domain structure, domain walls were usually subdivided into several segments with opposite polarities of magnetization rotation. |
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| Keywords: | domain structure micromagnetic modelling pseudo-single domain rock magnetism |
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