论文标题
活跃的偶极胶体在三个维度：弦，床单，迷宫质地和晶体
Active Dipolar Colloids in Three Dimensions: Strings, Sheets, Labyrinthine Textures and Crystals
论文作者
论文摘要
活性物质表现出令人惊讶的行为，让人联想起生物和分子液，并且在药物输送或以微米尺度混合中有希望的应用。活跃的胶体系统提供了重要模型，具有简单可控的相互作用，适合理论和计算机模拟。实验工作以相对较低的浓度下的（准）二维（2D）系统主导，而在与运动诱导的相位分离或模拟形态发生的浓度下，3D病例对3D病例的了解较少。在这里，我们研究了一个活性胶体的3D实验系统，密集的悬浮液中的体积分数为0.5。我们系统中的颗粒在交流电场下的横向平面中自我呈现。此外，该领域诱导了电偶极子，活动与空间与偶极相互作用之间的竞争会导致相位行为从活性气体到动态迷宫相，以及密集的四方和六角形晶体。中间体积分数的特征是二维片，使人想起活性膜。这些主动板沿垂直于应用场的方向折断对称性。此外，电场与粒子动力学之间的关系以复杂而出乎意料的方式取决于状态图中的位置。
Active matter exhibits striking behaviour reminiscent of living matter and molecular fluids, and has promising applications in drug delivery or mixing at the micron scale. Active colloidal systems provide important models with simple and controllable interactions amenable to theory and computer simulation. Experimental work is dominated by (quasi) two--dimensional (2d) systems at relatively low concentration, and rather less is known of the 3d case at concentrations pertinent to motility induced phase separation or to mimic morphogenesis. Here we investigate a 3d experimental system of active colloids in a dense suspension up to volume fractions of 0.5. The particles in our system are self-propelled in the lateral plane under an AC electric field. The field in addition induces an electric dipole, and the competition between activity and both steric and dipolar interactions gives rise to phase behaviour ranging from an active gas to a dynamic labyrinthine phase as well as dense tetragonal and hexagonal crystals. Intermediate volume fractions are characterised by two--dimensional sheets with large fluctuations reminiscent of active membranes. These active sheets break symmetry in a direction perpendicular to the applied field. Moreover, the relationship between electric field and the particle dynamics depends in a complex and unexpected manner upon the position in the state diagram.
