Micromagnetic simulation of structure-property relations in hard and soft
W. Scholz, D. Suess, T. Schrefl, and J. Fidler
Computational Materials Science, 18 (2000) 1-6.
Finite element micromagnetics describes the influence of the microstructure
on the magnetic properties of thin film nano-elements and permanent magnets.
The particle shape and the grain structure influence both the coercive
field and the reversal time of NiFe and Co nano-elements. The performances
of a Runge¯Kutta method and a semi-implicit backward difference method
for the time integration of the Gilbert equation of motion are compared.
In an array of closely packed patterned elements, the magnetostatic interactions
lead to a spread in the switching field depending on the magnetic state
of the neighbors. The effect of the magnetostatic interaction on magnetization
reversal can be effectively treated using a hybrid finite element/boundary
element method. The very same method is applied to simulate magnetostatic
interactions between the particles of a bonded magnet. The magnetostatic
interaction field decreases both the remanence and the coercive field of
nanocomposite magnets. In hard magnets, domain walls may be pinned at grain
boundaries between misoriented grains. The simulation of domain wall motion
requires adaptive refinement and coarsening of the mesh, in order to keep
the number of degrees of freedom reasonably low.
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Feb. 13, 2001