Wu Jin-Sheng, Lázaro Marina Torres, Mundoor Haridas, Wensink Henricus H, Smalyukh Ivan I
Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO, USA.
Laboratoire de Physique des Solides - UMR 8502, Université Paris-Saclay & CNRS, Orsay, France.
Nat Commun. 2024 Nov 16;15(1):9941. doi: 10.1038/s41467-024-54236-8.
Biaxial nematic liquid crystals are fascinating systems sometimes referred to as the Higgs boson of soft matter because of experimental observation challenges. Here we describe unexpected states of matter that feature biaxial orientational order of colloidal supercritical fluids and gases formed by sparse rodlike particles. Colloidal rods with perpendicular surface boundary conditions exhibit a strong biaxial symmetry breaking when doped into conventional chiral nematic fluids. Minimization of free energy prompts these particles to orient perpendicular to the local molecular director and the helical axis, thereby imparting biaxiality on the hybrid molecular-colloidal system. The ensuing phase diagram features colloidal gas and liquid and supercritical colloidal fluid states with long-range biaxial orientational symmetry, as supported by analytical and numerical modeling at all hierarchical levels of ordering. Unlike for nonchiral hybrid systems, dispersions in chiral nematic hosts display biaxial orientational order at vanishing colloid volume fractions, promising both technological and fundamental research utility.
双轴向列型液晶是迷人的体系，由于实验观测挑战，有时被称为软物质的希格斯玻色子。在此，我们描述了由稀疏棒状颗粒形成的胶体超临界流体和气体的双轴取向有序所特有的意外物质状态。具有垂直表面边界条件的胶体棒在掺杂到传统手性向列型流体中时会表现出强烈的双轴对称破缺。自由能的最小化促使这些颗粒垂直于局部分子指向矢和螺旋轴取向，从而赋予混合分子 - 胶体系统双轴性。由此产生的相图具有长程双轴取向对称性的胶体气体、液体和超临界胶体流体状态，这在所有层次的有序分析和数值模拟中都得到了支持。与非手性混合系统不同，手性向列型主体中的分散体在胶体体积分数为零时显示出双轴取向有序，这在技术和基础研究方面都具有应用前景。
