Field-driven metamorphoses of isolated skyrmions within the conical state of cubic helimagnets
Field-driven metamorphoses of isolated skyrmions within the conical state of cubic helimagnets
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DOI：
10.1103/physrevb.104.064432
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发表时间：
2021-08-18
影响因子：
3.7
通讯作者：
Smalyukh, Ivan I.
中科院分区：
文献类型：
--
作者：
Leonov, Andrey O.;Pappas, C.;Smalyukh, Ivan I.
拓扑稳定的场构型出现在物理学的许多领域，从基本粒子到凝聚态物质和宇宙学。这些系统中大量不同孤子态的深层物理关系和共同物理特征源于现象学方程的数学相似性。在过去的十年中，手性液晶和手性磁体在拓扑孤子的实验研究和对其非奇异场构型的理解中扮演了模型对象的角色。这与粒子状手性粒子的发现直接相关，它们也被认为是技术应用的有前途的成分。在这里，我们引入了一个简单的天幕子网络范例，其组成孤立天幕子的方向相互正交。一方面，这种网络被设想为一种基于自旋电子器件的新概念，例如，基于彼此之间无间隙的skyrmion运动，并且可能负责体立方helimagnets有序温度附近的前驱现象。特别地，我们证明了相互正交的skyrmions之间的相互转换：水平skyrmions可以旋转成中间的弹簧状态，随后挤压成具有两个极性的垂直skyrmions。另一方面，skyrmion管被认为是具有更复杂内部结构的类粒子状态的基石。由于垂直天幕和水平天幕之间的相互作用能趋于最小，形成了一组目标天幕，其中包括一种迄今为止被忽视的具有多重拓扑电荷的类型。圆锥形阶段为考虑的skyrmion进化提供了合适的背景。它确证了粒子网络中相互吸引的粒子相互作用，塑造了它们的内部结构，并指导了成核过程。另外，孤立的skyrmions的复杂纹理变化不仅会导致宿主圆锥形状态的结构变形，还可能导致以成对的meons为核心的奇异skyrmions秩序的形成。一般来说，这项工作提供的基本见解强调了skyrion变形的三维特征，也可以扩展到三维孤子，如hopfions。
Topologically stable field configurations appear in many fields of physics, from elementary particles to condensed matter and cosmology. Deep physical relations and common physical features of a large variety of very different solitonic states in these systems arise from the mathematical similarity of phenomenological equations. During the last decade, chiral liquid crystals and chiral magnets took on the role of model objects for the experimental investigation of topological solitons and the understanding of their nonsingular field configurations. This is directly related to the discovery of particle-like chiral skyrmions, which are also considered as promising ingredients for technological applications. Here we introduce a paradigm of facile skyrmionic networks with mutually orthogonal orientations of constituent isolated skyrmions. On the one hand, such networks are envisioned as a novel concept of spintronic devices based, e.g., on gapless skyrmion motion along each other, and are presumably responsible for precursor phenomena near the ordering temperatures of bulk cubic helimagnets. In particular, we demonstrate an interconversion between mutually orthogonal skyrmions: horizontal skyrmions may swirl into an intermediate spring-like state and subsequently squeeze into vertical skyrmions with both polarities. On the other hand, skyrmion tubes are considered as building blocks for particle-like states with more involved internal structure. A family of target-skyrmions, which includes a so far overlooked type with a multiple topological charge, is formed owing to the tendency to minimize the interaction energy between vertical and horizontal skyrmions. The conical phase serves as a suitable background for considered skyrmion evolution. It substantializes the attracting skyrmion-skyrmion interaction in the skyrmionic networks, shapes their internal structure, and guides the nucleation processes. Alternatively, intricate textural changes of isolated skyrmions result not only in the structural deformations of a host conical state, but may lead to the formation of an exotic skyrmion order with pairs of merons being the core of the game. Generically, the fundamental insights provided by this work emphasize a three-dimensional character of skyrmion metamorphoses and can also be extended to three-dimensional solitons, such as hopfions.