| Summary: | 碩士 === 國立雲林科技大學 === 材料科技研究所 === 104 === In this thesis, we investigated magnetic vortex wall motions driven by magnetic field in long nanostripes using micromagnetic simulation method. The main purpose of the study was to examine how the characteristics of vortex walls such as handedness affect wall stability under applied fields. All simulated nanostripes have the same length 12 m but with different widths ranging from 150 to 600 nm. The simulations were performed using GPU-accelerated open-source package MuMAX3.
The simulated results show that for narrow stripes (width 150 and 300 nm) the stability of vortex walls depends on their handedness (left- or right-handedness) and wall configurations (head-to-head or tail-to-tail). For head-to-head configuration, right-handed vortex walls can move smoothly under applied field, but left-handed vortex walls will annihilate at the stripe boundary and reborn as right-handed ones. Oppositely, for tail-to-tail configuration, only left-handed vortex walls can exist stably under applied filed. In the case of wider stripes (width 450 and 600 nm), the dynamics of vortex wall motion became more complex, involving vortex/anti-vortex pair creation at the center of the stripe and pair annihilation at the lateral boundary periodically. Handedness plays a minor role during such process. Moreover, as expected, no matter what the widths of the stripes, the total winding number was kept zero.
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