Liu Qingkun, Ackerman Paul J, Lubensky Tom C, Smalyukh Ivan I
Department of Physics, University of Colorado, Boulder, CO 80309;
Department of Physics, University of Colorado, Boulder, CO 80309; Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, CO 80309;
Proc Natl Acad Sci U S A. 2016 Sep 20;113(38):10479-84. doi: 10.1073/pnas.1601235113. Epub 2016 Sep 6.
The design and practical realization of composite materials that combine fluidity and different forms of ordering at the mesoscopic scale are among the grand fundamental science challenges. These composites also hold a great potential for technological applications, ranging from information displays to metamaterials. Here we introduce a fluid with coexisting polar and biaxial ordering of organic molecular and magnetic colloidal building blocks exhibiting the lowest symmetry orientational order. Guided by interactions at different length scales, rod-like organic molecules of this fluid spontaneously orient along a direction dubbed "director," whereas magnetic colloidal nanoplates order with their dipole moments parallel to each other but pointing at an angle to the director, yielding macroscopic magnetization at no external fields. Facile magnetic switching of such fluids is consistent with predictions of a model based on competing actions of elastic and magnetic torques, enabling previously inaccessible control of light.
设计并实际实现出在介观尺度上兼具流动性和不同有序形式的复合材料，是重大的基础科学挑战之一。这些复合材料在技术应用方面也具有巨大潜力，涵盖从信息显示到超材料等领域。在此，我们介绍一种流体，其中有机分子和磁性胶体构建单元共存着极性和双轴有序，呈现出最低对称性的取向有序。在不同长度尺度相互作用的引导下，这种流体中棒状有机分子会自发地沿着一个被称为“指向矢”的方向排列，而磁性胶体纳米片则以其偶极矩相互平行但与指向矢呈一定角度的方式排列，从而在无外部磁场的情况下产生宏观磁化。这种流体的简便磁开关特性与基于弹性和磁转矩竞争作用的模型预测相符，能够实现此前难以达成的光控制。
