Ferroelectric nematic droplets in their isotropic melt
Ferroelectric nematic droplets in their isotropic melt
复制标题
各向同性熔体中的铁电向列相液滴
DOI：
10.1039/d2sm01395a
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发表时间：
2023
期刊：
影响因子：
3.4
通讯作者：
Jákli, Antal
中科院分区：
文献类型：
--
作者：
Perera, Kelum;Saha, Rony;Nepal, Pawan;Dharmarathna, Rohan;Hossain, Md Sakhawat;Mostafa, Md;Adaka, Alex;Waroquet, Ronan;Twieg, Robert J.;Jákli, Antal
早在一百多年前，人们就从理论上研究了铁电向列液体相变的各向同性，但实验研究很少。本文给出了铁电向列液晶液滴与各向同性熔体共存的新型机电效应的实验结果和理论考虑。我们发现，只要有增加横向液滴尺寸的空间，液滴具有扁平的煎饼状形状，比样品厚度薄。在液滴的中心存在一个低双折射的翼状缺陷，该缺陷垂直于平面内弱电场，然后在更高的电场中扩展并分裂为两个。与缺陷的运动和扩展平行，整个液滴沿着电场漂移，其速度与液滴的大小无关，与电场的振幅成正比。当电场增大到1 mV μm−1以上时，液滴整体发生变形，并随电场振荡。这些观察使我们确定了极化场，并揭示了由于缺陷体积周围的极化发散而存在一对正负束缚电荷。
The isotropic to ferroelectric nematic liquid transition was theoretically studied over one hundred years ago, but its experimental studies are rare. Here we present experimental results and theoretical considerations of novel electromechanical effects of ferroelectric nematic liquid crystal droplets coexisting with the isotropic melt. We find that the droplets have flat pancake-like shapes that are thinner than the sample thickness as long as there is room to increase the lateral droplet size. In the center of the droplets a wing-shaped defect with low birefringence is present that moves perpendicular to a weak in-plane electric field, and then extends and splits in two at higher fields. Parallel to the defect motion and extension, the entire droplet drifts along the electric field with a speed that is independent of the size of the droplet and is proportional to the amplitude of the electric field. After the field is increased above 1 mV μm−1 the entire droplet gets deformed and oscillates with the field. These observations led us to determine the polarization field and revealed the presence of a pair of positive and negative bound electric charges due to divergences of polarization around the defect volume.