Topological solitons, cholesteric fingers and singular defect lines in Janus liquid crystal shells
Topological solitons, cholesteric fingers and singular defect lines in Janus liquid crystal shells
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Janus液晶壳中的拓扑孤子、胆甾指和奇异缺陷线
DOI：
10.1039/c9sm02033k
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Lopez-Leon, Teresa
中科院分区：
文献类型：
--
作者：
Durey, Guillaume;Sohn, Hayley R.;Ackerman, Paul J.;Brasselet, Etienne;Smalyukh, Ivan I.;Lopez-Leon, Teresa
拓扑孤子是场中的非奇异但拓扑非平凡的结构，与奇异缺陷类似，在物理学的各个领域都有着重要的意义。奇异和孤子拓扑结构的产生和观测在大多数科学分支中仍然是一项复杂的任务-但在软物质物理学中，它们可以在液晶的指向矢场中实现。此外，它已被证明，使用微流体将液晶限制到球壳导致了一个多功能的实验平台，用于动态研究指向矢配置之间的拓扑变换。在这项工作中，我们展示了触发形成的拓扑孤子，双指，奇异缺陷线和相关结构的液晶壳。我们表明，以适应这些对象，壳必须具有Janus性质，具有扭曲和untwisted域。我们报告形成的线性和轴对称的对象，我们确定为brachfingers和skyrmions或基本torons，分别。然后，我们利用壳对众多外部刺激的敏感性来诱导各种类型的结构之间的动态过渡，从而比具有固体平坦壁的传统液晶单元提供更丰富的现象学。使用逐渐更精细的实验技术，我们诱导的有针对性的改造，螺旋扭曲的墙壁和手指到skyrmions和基本torons。我们捕捉这些导演变换的不同阶段，使用数值模拟。最后，我们揭示了一个实验机制，成核阵列的轴对称结构的外壳，从而创建一个系统的潜在利益，解决弯曲空间的晶体学研究。
Topological solitons are non-singular but topologically nontrivial structures in fields, which have fundamental significance across various areas of physics, similar to singular defects. Production and observation of singular and solitonic topological structures remain a complex undertaking in most branches of science – but in soft matter physics, they can be realized within the director field of a liquid crystal. Additionally, it has been shown that confining liquid crystals to spherical shells using microfluidics resulted in a versatile experimental platform for the dynamical study of topological transformations between director configurations. In this work, we demonstrate the triggered formation of topological solitons, cholesteric fingers, singular defect lines and related structures in liquid crystal shells. We show that to accommodate these objects, shells must possess a Janus nature, featuring both twisted and untwisted domains. We report the formation of linear and axisymmetric objects, which we identify as cholesteric fingers and skyrmions or elementary torons, respectively. We then take advantage of the sensitivity of shells to numerous external stimuli to induce dynamical transitions between various types of structures, allowing for a richer phenomenology than traditional liquid crystal cells with solid flat walls. Using gradually more refined experimental techniques, we induce the targeted transformation of cholesteric twist walls and fingers into skyrmions and elementary torons. We capture the different stages of these director transformations using numerical simulations. Finally, we uncover an experimental mechanism to nucleate arrays of axisymmetric structures on shells, thereby creating a system of potential interest for tackling crystallography studies on curved spaces.