Hysteresis and switching dynamics of patterned magnetic elements
T. Schrefl, J. Fidler, D. Süss, and W. Scholz
Journal Physica B-Condensed Matter 275 (2000) 55-58.
The hystersis properties and the switching time of Co nano-elements
were calculated using finite element micromagnetics. The calculated coercive
field of 200×40×25 nm Co nano-elements strongly depends on
the model of the polycrystalline microstructure assumed in the simulations.
For small, randomly oriented grains the magnetocrystalline anisotropy may
be neglected, since the effective anisotropy vanishes due to averaging.
Quasistatic simulations of magnetization reversal show that taking
anisotropy into account favors the formation of vortices and therefore
reduces the coercive field from 140 to 95 kA/m. Vortices immediately
form after the application of a reversed field, assuming a polycrystalline
microstructure. For an applied field close to the coercive field,
vortices form only after a certain waiting time.
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Feb. 13, 2001