Pandey M B, Porenta T, Brewer J, Burkart A, Copar S, Zumer S, Smalyukh Ivan I
Department of Physics and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, VSSD College, Kanpur 208 002, India.
Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Jun;89(6):060502. doi: 10.1103/PhysRevE.89.060502. Epub 2014 Jun 30.
We describe dipolar nematic colloids comprising mutually bound solid microspheres, three-dimensional skyrmions, and point defects in a molecular alignment field of chiral nematic liquid crystals. Nonlinear optical imaging and numerical modeling based on minimization of Landau-de Gennes free energy reveal that the particle-induced skyrmions resemble torons and hopfions, while matching surface boundary conditions at the interfaces of liquid crystal and colloidal spheres. Laser tweezers and videomicroscopy reveal that the skyrmion-colloidal hybrids exhibit purely repulsive elastic pair interactions in the case of parallel dipoles and an unexpected reversal of interaction forces from repulsive to attractive as the center-to-center distance decreases for antiparallel dipoles. The ensuing elastic self-assembly gives rise to colloidal chains of antiparallel dipoles with particles entangled by skyrmions.
我们描述了由相互结合的固体微球、三维斯格明子以及手性向列型液晶分子排列场中的点缺陷组成的偶极向列型胶体。基于朗道 - 德热纳自由能最小化的非线性光学成像和数值模拟表明，粒子诱导的斯格明子类似于环面子和霍普夫子，同时在液晶与胶体球的界面处匹配表面边界条件。激光镊子和视频显微镜显示，在平行偶极的情况下，斯格明子 - 胶体杂化物表现出纯粹的排斥性弹性对相互作用，而对于反平行偶极，随着中心距减小，相互作用力会出现从排斥到吸引的意外反转。由此产生的弹性自组装形成了反平行偶极的胶体链，粒子被斯格明子缠绕。
