Trochoidal motion and pair generation in skyrmion and antiskyrmion dynamics under spin–orbit torques
Trochoidal motion and pair generation in skyrmion and antiskyrmion dynamics under spin–orbit torques
复制标题
DOI：
10.1038/s41928-018-0114-0
复制
发表时间：
2018-03
影响因子：
34.3
通讯作者：
U. Ritzmann;Stephan von Malottki;Joo-Von Kim;S. Heinze;J. Sinova;B. Dupé
中科院分区：
文献类型：
--
作者：
U. Ritzmann;Stephan von Malottki;Joo-Von Kim;S. Heinze;J. Sinova;B. Dupé
磁性skyrmions是旋转的磁性自旋结构，可用于构建下一代存储器和逻辑设备。它们可以用拓扑荷来表征，拓扑荷描述了自旋如何缠绕在核心周围。具有相反拓扑电荷的skyrmions和antiskyrmions的动力学通常通过假设刚性核来描述。然而，这减少了描述Skyrmion运动的变量集。在这里，我们从理论上探讨的动力学的skyrmion和antiskyrmion的铁磁薄膜，并表明，电流引起的自旋-轨道力矩可以导致余摆线运动和skyrmion-antiskyrmion对生成，这只发生在任何skyrmion或antiskyrmion，取决于对称性的基础Dzyaloshinskiiii-Moriya相互作用。这样的动力学是由核心变形引起的，导致了一个依赖于时间的螺旋度，它控制着Skyrmion和antiskyrmion核心的运动。我们计算的动力学相图，通过结合原子自旋模拟，减少变量建模和机器学习算法。它预测了自旋轨道力矩如何控制运动的类型以及通过反skyrmion播种产生skyrmion晶格的可能性。
Magnetic skyrmions are swirling magnetic spin structures that could be used to build next-generation memory and logic devices. They can be characterized by a topological charge that describes how the spin winds around the core. The dynamics of skyrmions and antiskyrmions, which have opposite topological charges, are typically described by assuming a rigid core. However, this reduces the set of variables that describe skyrmion motion. Here we theoretically explore the dynamics of skyrmions and antiskyrmions in ultrathin ferromagnetic films and show that current-induced spin–orbit torques can lead to trochoidal motion and skyrmion–antiskyrmion pair generation, which occurs only for either the skyrmion or antiskyrmion, depending on the symmetry of the underlying Dzyaloshinskii–Moriya interaction. Such dynamics are induced by core deformations, leading to a time-dependent helicity that governs the motion of the skyrmion and antiskyrmion core. We compute the dynamical phase diagram through a combination of atomistic spin simulations, reduced-variable modelling and machine learning algorithms. It predicts how spin–orbit torques can control the type of motion and the possibility to generate skyrmion lattices by antiskyrmion seeding.