论文标题
Skyrmion弦的散装和表面拓扑指数
Bulk and surface topological indices for a skyrmion string
论文作者
论文摘要
磁性天空是一种拓扑磁性涡流，其拓扑性质的特征是称为Skyrmion编号的索引，它是在二维空间上定义为单位球体上定义的磁矩的映射。在三维中，有一个天空，即涡旋磁体自然形成弦，该涡流在磁铁的表面或大块中终止。对于这样的字符串，控制其拓扑稳定性的拓扑指数较小。在这里，我们从理论上表明，在膜样本中，skyrmion弦的电流驱动运动的数值模拟，表面边缘在表面上，与稳定性相关的拓扑指数是以下内容； （i）沿开发表面的天空数，以及（ii）散装中的单子电荷定义为封闭奇异磁性构型的表面上的积分。只要磁构型缓慢变化，前者就可以保守，而其变化与非零单极电荷有关。 Skyrmion数量和单盘电荷提供了对拓扑磁纹理的稳定性和Skyrmion弦的非平凡动力学的连贯理解。
The magnetic skyrmion is a topological magnetic vortex, and its topological nature is characterized by an index called skyrmion number which is a mapping of the magnetic moments defined on a two-dimensional space to a unit sphere. In three-dimensions, a skyrmion, i.e., a vortex penetrating though the magnet naturally forms a string, which terminates at the surfaces of the magnet or in the bulk. For such a string, the topological indices, which control its topological stability are less trivial. Here, we show theoretically, in terms of numerical simulation for the current-driven motion of a skyrmion string in a film sample with the step edges on the surface, that the topological indices relevant to the stability are the followings; (i) skyrmion number along the developed surface, and (ii) the monopole charge in the bulk defined as the integral over the surface enclosing a singular magnetic configuration. As long as the magnetic configuration is slowly varying, the former is conserved while its changes is associated with nonzero monopole charge. The skyrmion number and the monoplole charge offer a coherent understanding of the stability of the topological magnetic texture and the nontrivial dynamics of skyrmion strings.
