论文标题

螺旋,涡流和刺猬之间由手性磁铁中的空间各向异性驱动的螺旋

Phase transitions between helices, vortices, and hedgehogs driven by spatial anisotropy in chiral magnets

论文作者

Shimizu, Kotaro, Okumura, Shun, Kato, Yasuyuki, Motome, Yukitoshi

论文摘要

旋转螺旋的叠加可以产生拓扑旋转纹理,例如二维涡旋和天空和三维刺猬。它们的拓扑性质和空间维度取决于组成螺旋的数量和相对方向。这允许通过控制空间各向异性在拓扑自旋纹理之间相互转换。在这里,我们从理论上研究了手性磁力的有效自旋模型中各向异性在磁相互作用中的影响。通过两种三重和四倍叠加的病例的差异计算,我们发现在各向同性情况下稳定的刺猬晶格被各向异性变形,并最终变成其他具有降低尺寸的旋转纹理,例如螺旋和旋转和涡流。我们还通过追踪磁性和抗巨孔的真实空间位置以及非稳态旋转纹理产生的新兴磁场来阐明拓扑性能的变化。我们的结果表明,可以通过手性材料中的单轴压力和化学替代来控制拓扑自旋纹理。

Superpositions of spin helices can yield topological spin textures, such as two-dimensional vortices and skyrmions, and three-dimensional hedgehogs. Their topological nature and spatial dimensionality depend on the number and relative directions of the constituent helices. This allows mutual transformation between the topological spin textures by controlling the spatial anisotropy. Here we theoretically study the effect of anisotropy in the magnetic interactions for an effective spin model for chiral magnetic metals. By variational calculations for both cases with triple and quadruple superpositions, we find that the hedgehog lattices, which are stable in the isotropic case, are deformed by the anisotropy, and eventually changed into other spin textures with reduced dimension, such as helices and vortices. We also clarify the changes of topological properties by tracing the real-space positions of magnetic monopoles and antimonopoles as well as the emergent magnetic field generated by the noncoplanar spin textures. Our results suggest possible control of the topological spin textures, e.g., by uniaxial pressure and chemical substitution in chiral materials.

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