近日，意大利米兰大学的Tommaso Bellini及其研究小组与Matthew A.Glaser等人合作，并取得一项新进展。经过不懈努力，他们实现了受限铁电向列中的流体超筛和极化跟随。相关研究成果已于2023年7月27日在国际知名学术期刊《自然—物理学》上发表。

该研究团队通过将一个小电场应用于约束在通过直线和弯曲路径连接电极的微通道中的铁电向列线，以探测N_F相位，并发现N_F相位平滑地按照其极化顺序跟随通道，与它们缠绕路径无关。这意味着电场的相应行为。当电场反转时，极性顺序经历了一个以静电相互作用为主的多级转换过程。

研究人员还在通道受限NF液晶的准二维连续介质模型中发现了多级极化开关动力学，从而可以探索其内部结构和电气自组织。这表明极化对准和电场导向是流体超筛的直接结果，通过极化重定向迅速消除垂直于通道壁的电场分量。这种响应模拟了超高介电常数介质的预期行为，但具有流体铁电体特有的电荷积累和局部有序模式。

据悉，最近发现的铁电向列相（N_F）液晶相表现出自发极化场，该场在方向上像液晶一样流动并且在大小上像固体铁电体一样大。这种组合赋予此相独特的的静电现象以及对应用场的响应。

附：英文原文

Title: Fluid superscreening and polarization following in confined ferroelectric nematics

Author: Caimi, Federico, Nava, Giovanni, Fuschetto, Susanna, Lucchetti, Liana, Pai, Petra, Osellame, Roberto, Chen, Xi, Clark, Noel A., Glaser, Matthew A., Bellini, Tommaso

Issue&Volume: 2023-07-27

Abstract: The recently discovered ferroelectric nematic (N_F) liquid-crystal phase exhibits a spontaneous polarization field that is both orientationally fluid like a liquid crystal and large in magnitude like a solid ferroelectric. This combination imparts this phase with a unique electrostatic phenomenology and response to applied fields. Here we probe this phase by applying a small electric field to ferroelectric nematics confined in microchannels that connect electrodes through straight and curved paths and find that the N_F phase smoothly orders with its polarization following the channels despite their winding paths. This implies a corresponding behaviour of the electric field. On inversion of the electric field, the polar order undergoes a multistage switching process dominated by electrostatic interactions. We also find multistage polarization switching dynamics in the numerical simulations of a quasi-two-dimensional continuum model of channel-confined NF liquid crystals, enabling the exploration of their internal structural and electrical self-organization. This indicates that polarization alignment and electric-field guiding are direct consequences of fluid superscreening—the prompt elimination of electric-field components normal to the channel walls by polarization reorientation. This response mimics the behaviour expected for ultrahigh-permittivity dielectrics, but with patterns of charge accumulation and local ordering unique to fluid ferroelectrics.

DOI: 10.1038/s41567-023-02150-z

Source: https://www.nature.com/articles/s41567-023-02150-z