垂直各向异性多层膜中边界控制的单个磁skyrmion的产生、移动及湮灭机制研究

磁skyrmions是一种拓扑稳定且表现出粒子特性的手性自旋构型,在超高密度信息存储领域具有很好的应用前景。本项目选取一种有望实现室温下对skyrmions进行操控的体系——垂直各向异性多层膜为研究对象，重点关注边界条件对单个skyrmion的产生、移动及湮灭的影响。我们将首先计算不同边界的纳米结构的稳态磁构型与磁各向异性- Dzyaloshinskii-Moriya相互作用的关系相图，观察各种磁构型随磁场、电流的演化过程，得出边界条件对单个skyrmion的存在范围、尺寸和稳定性的影响机制，并找出利用磁场和电流控制其生成和湮灭的方法。然后对skyrmions生成和湮灭的动态过程进行细致模拟，揭示边界条件对其微观机制的影响。最后通过计算不同形态纳米结构中单个skyrmion的动力学行为，揭示边界效应、Rashba效应和自旋霍尔效应在自旋转移扭矩驱动skyrmions中的作用。

Magnetic skyrmions are topologically stable and particle-like chiral spin configuration. They are appealing because of their potential applications to ultra-dense information storage. In this project, we adopt the magnetic multilayers with perpendicular magnetic anisotropy, which is a candidate for achieving control of skyrmions at room temperature, as the research objects. Moreover, we focus on the influence of the boundary on the nucleation, motion and annihilation mechanism of a single magnetic skyrmion. We first calculate the phase diagrams of magnetic configuration in nanostructures with different boundary conditions as the functions of the magnetic anisotropy and the Dzyaloshinskii-Moriya interaction, and then simulate the evolution processes of different magnetic configurations under the effects of magnetic fields or currents. Accordingly, we conclude the influence mechanism of the boundary conditions on the parameter regions where the skyrmion is stable, size and the stability of single skyrmion. Further, we work out the methods to manipulate the nucleation and annihilation of skyrmions, and reveal the dependence of the correspondingly micromechanism on the boundary condition by simulating the dynamic processes meticulously. Finally, we study the dynamics of skyrmions in different conditions, and then explain how the boundary condition, the Rashba effect and the spin Hall effect influence the skyrmion motion driven by the spin transfer torque.