Petroff Alexander P, Whittington Christopher, Kudrolli Arshad
Department of Physics, Clark University, Worcester, Massachusetts 01610, USA.
Phys Rev E. 2023 Jul;108(1-1):014609. doi: 10.1103/PhysRevE.108.014609.
We demonstrate that edge currents develop in active chiral matter due to boundary shielding over a wide range of densities corresponding to a gas, fluid, and crystal. The system is composed of spinning disk-shaped grains with chirally arranged tilted legs confined in a circular vibrating chamber. The edge currents are shown to increasingly drive circulating bulk flows with area fraction as percolating clusters develop due to increasing spin-coupling between neighbors mediated by frictional contacts. Edge currents are observed even in the dilute limit. While, at low area fraction, the average flux vanishes except within a distance that is of the order of a particle diameter of the boundary, the penetration depth grows with increasing area fraction until a solid-body rotation is achieved corresponding to the highest packing, where the particles are fully caged with hexagonal order and spin in phase with the entire packing. A coarse-grained model, based on the increased collisional interlocking of the particles with area fraction and the emergence of order, captures the observed flow fields.
我们证明，由于在对应于气体、流体和晶体的广泛密度范围内的边界屏蔽，活性手性物质中会产生边缘电流。该系统由自旋的盘状颗粒组成，这些颗粒具有手性排列的倾斜支腿，被限制在一个圆形振动腔内。结果表明，随着由摩擦接触介导的相邻颗粒之间的自旋耦合增加，渗流团簇形成，边缘电流越来越多地驱动循环体流。即使在稀释极限下也能观察到边缘电流。在低面积分数时，除了在边界颗粒直径量级的距离内，平均通量消失，穿透深度随着面积分数的增加而增加，直到达到对应于最高堆积的刚体旋转，此时颗粒以六边形有序完全被束缚，并与整个堆积同相自旋。一个基于颗粒与面积分数之间碰撞联锁增加以及有序出现的粗粒度模型，捕捉到了观测到的流场。
