几何受限磁体中skyrmion的形成与动力学调控研究

Magnetic skyrmions have recently become a hot topic in condensed matter physics, due to a variety of intriguing topological phenomena and properties emerging from their topological spin structures, as well as their promising applications in spintronic devices. Skyrmions in confined geometries provide a new and ideal platform for exploring their new physical effects and potential applications, which deserves greater research attention. Therefore, this proposal aims at studying the formation and stability of skyrmions in confined geometries, as well as their dynamics including motion, creation and annihilation. Special attention is paid to address several major issues of new physical effects and the underlying mechanism emerging from the skyrmions in confined geometries, including: (1) Manipulating the formation and dynamics of skyrmions by synthetically adjusting the intrinsic parameters of magnets and ambient conditions (and/or external stimuli), in which the roles of geometric shapes and sizes of the sample in the skyrmion formation and dynamics will be highlighted and revealed; (2) Exploring methods and conditions to access the metastable skyrmions, and investigating their stability and dynamics behaviors brought about by external stimuli; (3) Exploring the interaction between skyrmions (or the interactions between skyrmion and other topological defects), and the unusual dynamics behaviors occurring in the collision process. In addition, some new effective approaches to skyrmion manipulation will be proposed, which could provide theoretical guides and experimental schemes for designing the skyrmion-based spintronic devices.

磁性skyrmion拓扑结构蕴含丰富的奇特拓扑现象和特性，在自旋电子器件方面有潜在应用价值，成为当前凝聚态物理的研究热点。几何受限磁体为探索skyrmion新物理效应和潜在应用提供崭新和理想的平台，具有重要研究意义。本项目以几何受限磁体中的skyrmion为研究对象，关注其形成、稳定性及在外界干扰作用下的动力学行为（包括产生、湮灭及运动状态），着重揭示skyrmion出现的新物理效应及其物理机制，包括：（1）通过综合调用内禀和外部参量调控skyrmion的形成及动力学行为，尤其注重利用几何形状和尺寸的重要调控作用；（2）探索形成亚稳skyrmion态的方法和条件，揭示其在外界干扰作用下的稳定性及动力学行为；（3）探索skyrmion之间或与其它拓扑缺陷态之间的相互作用及相互碰撞中出现的新动力学行为。在此基础上发展新的调控方法，为设计基于skyrmion的自旋电子器件提供理论基础和实验方案。

本项目研究了几何受限磁体中skyrmion和涡旋拓扑自旋结构的形成和动力学行为。主要研究内容和结果包括：(1)手征磁体中compass各向异性对螺旋磁结构和skyrmion晶体的调控；(2)手征性方形纳米磁体中拓扑荷|Q|=1/4奇异“四分skyrmion”磁结构的形成及动力学调控；(3)椭圆纳米磁体中电控双涡旋磁畴写入和擦除；(4)缺陷和杂质对纳米圆盘中skyrmion动力学的调控。在这些研究中，我们重点揭示了其中出现的新物理现象及其物理机制，在此基础上发展调控skyrmion和涡旋的新方法，提出设计基于拓扑自旋结构信息存储单元、高存储密度新型自旋电子器件的有效方案，这些研究工作在新型自旋电子器件方面具有潜在的重要应用价值。此外，研究了修正自旋波理论在一维具有近邻和次近邻交换作用海森堡铁磁体中的应用，磁场和光通量对full-Heusler合金Co2FeAlSi薄膜中多重自旋波动力学的调控等，这些相关研究为探索skyrmion中自旋波动力学调控问题提供了理论基础和实验方案。