Skyrmion and meron ordering in quasi-two-dimensional chiral magnets
Skyrmion and meron ordering in quasi-two-dimensional chiral magnets
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DOI：
10.1103/physrevb.106.224428
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发表时间：
2022-12
影响因子：
3.7
通讯作者：
Natsuki Mukai;A. Leonov
中科院分区：
文献类型：
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作者：
Natsuki Mukai;A. Leonov
我们重新讨论了具有易轴单轴各向异性和外加磁场的二维手性磁体的著名理论相图。特别强调了具有分数拓扑电荷的摆线和六边形斯基子晶格之间相变的介子量子。具有相反拓扑电荷的两个耦合介子的局域态表现出非互反的电流驱动动力学：它没有斯基米子霍尔效应，但由于吸引介子势的不对称性，产生了不对称的电流速度特性。我们还解决了skyrmion排列成六边形和方形skyrmion晶体的问题。在整个场域范围内，正方形晶格在不同取向的六边形晶格之间呈现鞍点状态。分离细长天幕的介子也被证明通过形成一个六角形晶格遮蔽普通天幕晶格而形成局部能量最小值。此外，我们还关注了调制相位的各向异性驱动变换及其孤立对应，它们作为解的分离分支存在于临界各向异性值的两侧。此外，在该各向异性值附近可以找到具有两个旋转感觉的孤立的天球族。我们的结果从基础的角度来看是有用的，因为它们补充了以前的发现，从应用的角度来看，因为它们为开发基于介子的自旋电子器件提供了指导。
We revisit the well-known theoretical phase diagram for a two-dimensional chiral magnet with an easy-axis uniaxial anisotropy and an applied magnetic field. A particular emphasis is given to merons—quanta of the phase transition between the cycloid and the hexagonal skyrmion lattice, which possess fractional topological charges. A localized state of two coupled merons with opposite topological charges exhibits the nonreciprocal current-driven dynamics: it experiences no skyrmion Hall effect, but due to the asymmetry of the attracting intermeron potential gives rise to asymmetric current-velocity characteristics. We also address the problem of skyrmion ordering into hexagonal and square skyrmion crystals. In an entire field range, the square lattice turns out a saddle point state between differently oriented hexagonal lattices. Merons separating elongated skyrmions were also shown to form a local energy minimum by forming a hexagonal lattice shadowing the ordinary lattice of skyrmions. In addition, we focus on the anisotropy-driven transformations of modulated phases and their isolated counterparts, which exist as detached branches of solutions on both sides from the critical anisotropy value. Moreover, a family of isolated skyrmions with both rotational senses can be found near this anisotropy value. Our results are useful from both the fundamental point of view, since they complement previous findings, and from the point of view of applications, since they provide guidelines for developing meron-based spintronic devices.