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