Study of magnetization configuration and switching behavior in submicro-scaled asymmetric Permalloy ring
| Autor: | 鄭念佳 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 By introducing an inner hole with its center shifted along the diameter to a submicro-scaled NiFe ring, the symmetry of the ring was broken to achieve the flux-closure chirality control in the in-plane magnetic field. Series of asymmetric rings with different inner diameters and displacements were simulated to observe its magnetic switching behavior and the influence of asymmetry on the closed field and destruction field of the flux-closure state. Micromagnetic simulation and analysis work were performed by using the object oriented micromagnetic framework (OOMMF) on asymmetric permalloy rings. The diameter (D) and the thickness of the rings were 500 and 20 nm. The asymmetric ratio is defined as and can be changed by the inner diameters (d) and displacements (S) of asymmetric rings. We simulated magnetization configuration and switching behavior with the in-plane magnetic field and observed the relation of closed field and destruction field of the flux-closure state to the asymmetric ratio. When the thickness of the rings is 20 nm, the magnetic switching behavior of all samples is simple domain wall propagation reversal. Linear relations of the flux-closure closed field to asymmetric ratio were found that would be useful for controlling closed fields on purpose. However, in addition to the asymmetric ratio, the flux-closure destruction fields were influenced by the inner diameter. We must consider that the asymmetric ratio and the inner diameter two parameters, can achieve the goal to control the flux-closure destruction field. Finally, we changed the diameter of the rings. The results show the linear relationship between the asymmetric ratio and the flux-closure closed field with three different ring diameters. The reason for the relationship is explained through the view of the interactions between magnetic moments, the ring diameter is smaller, the interaction between magnetic moments is smaller, the ring will be quicker switches the flux-closure state. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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