Podoliak Natalia, Lejček Lubor, Cigl Martin, Novotná Vladimíra
Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 00 Prague 8, Czech Republic.
Soft Matter. 2025 Sep 12. doi: 10.1039/d5sm00747j.
The regulation of topological structures and pattern formation has attracted wide attention in the field of condensed matter. Liquid crystals (LCs), as a class of soft matter, uniquely combine fluidity with anisotropic properties, making them ideal systems for exploring defect dynamics. When confined systems are subjected to external stimuli, LCs can exhibit a variety of topological defects. The recent discovery of ferroelectric nematics (N), characterized by high permittivity and spontaneous polarization, has opened new possibilities for technological applications, enriching the landscape of accessible topological phenomena. In this study, we demonstrate the formation of tunable two-dimensional arrays of topological defects in an N compound, induced by an alternating electric field in sandwich cells without pre-patterning. These defects self-organize into pseudo-square lattices, with their character and periodicity governed primarily by the frequency of the applied field and, to a lesser extent, by the cell thickness. We attribute the emergence of these structures to the interplay between elastic and electric forces appearing as a result of polar molecular reorientation. Our findings offer a promising approach for generating reconfigurable, spatially periodic polarization patterns, with potential relevance to future soft-matter-based devices and tunable photonic systems.
拓扑结构的调控和图案形成在凝聚态物理领域引起了广泛关注。液晶（LCs）作为一类软物质，独特地将流动性与各向异性特性结合在一起，使其成为探索缺陷动力学的理想体系。当受限系统受到外部刺激时，液晶会表现出各种拓扑缺陷。最近发现的铁电向列相（N），具有高介电常数和自发极化特性，为技术应用开辟了新的可能性，丰富了可及拓扑现象的领域。在本研究中，我们展示了在没有预图案化的夹层单元中，由交变电场诱导在一种N化合物中形成可调谐的二维拓扑缺陷阵列。这些缺陷自组织成伪方形晶格，其特征和周期性主要由施加电场的频率决定，在较小程度上由单元厚度决定。我们将这些结构的出现归因于极性分子重新取向导致的弹性力和电力之间的相互作用。我们的发现为生成可重构的、空间周期性极化图案提供了一种有前景的方法，这与未来基于软物质的器件和可调谐光子系统潜在相关。
