Vojkovic S, Cacilhas R, Pereira A R, Altbir D, Núñez Á S, Carvalho-Santos V L
Instituto de Física, Pontificia Universidad Católica de Chile, Campus San Joaquín Av. Vicuña Mackena, 4860 Santiago, Chile.
Universidade Federal de Viçosa, Departamento de Física, Av. Peter Henry Rolfs s/n, 36570-000, Viçosa, MG, Brasil.
Nanotechnology. 2021 Apr 23;32(17):175702. doi: 10.1088/1361-6528/abd714.
Magnetic skyrmions are quasiparticle-like textures that are topologically different from a single domain magnetization state. Their topological protection, combined with the low current density needed to move them, make these objects relevant to be used as information storage structures. In such a context, the analysis of the interactions between skyrmions is interesting and relevant for future applications. In this work, through micromagnetic simulations and numerical calculations, we studied the interaction between two skyrmions living on different parallel ferromagnetic racetracks connected by an exchange-like interaction. The upper and lower racetracks are separated by a height offset and the interaction between the upper and the lower skyrmion is analyzed in terms of the magnetic and geometrical parameters. Three states are predicted, as a function of these parameters: scattered or free skyrmions, bound skymions, and annihilated skyrmions. Our results, presented in a phase diagram, demonstrate that even in the case here called free skyrmions, there is a small and brief interaction when both are close enough, but the skyrmion in the top layer does not drag the skyrmion in the bottom layer. For bound skyrmions, both keep linked during larger times. In the latter case, there are strong changes in the velocity of the skyrmions induced by the effect of a higher effective mass when both are coupled.
磁斯格明子是一种类似于准粒子的结构，其拓扑结构与单畴磁化状态不同。它们的拓扑保护特性，再加上移动它们所需的低电流密度，使得这些物体有望用作信息存储结构。在这种情况下，分析斯格明子之间的相互作用对于未来的应用具有重要意义。在这项工作中，我们通过微磁模拟和数值计算，研究了生活在由类交换相互作用连接的不同平行铁磁跑道上的两个斯格明子之间的相互作用。上下跑道由高度偏移隔开，并根据磁学和几何参数分析上下斯格明子之间的相互作用。根据这些参数预测了三种状态：散射或自由斯格明子、束缚斯格明子和湮灭斯格明子。我们在相图中展示的结果表明，即使在本文所谓的自由斯格明子的情况下，当两者足够接近时也会有短暂的小相互作用，但顶层的斯格明子不会拖动底层的斯格明子。对于束缚斯格明子，两者在较长时间内保持连接。在后一种情况下，当两者耦合时，由于有效质量增加的影响，斯格明子的速度会发生强烈变化。
