Pattern Formation and Stick-Slip Dynamics in Binary Particle Assemblies with Rotating Drives

TL;DR

This study numerically explores how binary particle systems with rotating drives form various patterns and undergo order-disorder transitions, revealing complex lane formations, switching behaviors, and effects of temperature and interaction potentials.

Contribution

It uncovers novel pattern formation and switching phenomena in driven binary particle assemblies, expanding understanding of nonequilibrium self-organization in such systems.

Findings

Pattern forming states include stripes, jammed states, and phase-separated fluids.

Order-disorder transitions are linked to rotation frequency and drive phase relations.

High-frequency drives can induce patterned flow and local recrystallization.

Abstract

We numerically examine a binary system of particles with repulsive interactions, where one species is driven by a rotating drive and the other is subjected either to a constant drive in a fixed direction or to a rotating drive that is out of phase with the first species. As a function of rotation frequency, we find a variety of order-disorder transitions and pattern forming states, including density-modulated stripes, partially jammed states, phase separated fluids, and mixed fluids. When one species has a constant drive and the drive on the other species is rotated at low frequencies, the system switches between different pattern forming phase-separated lanes including density-modulated stripes and partially jammed states, similar to what is observed for oppositely driven colloids. The lanes tend to align with the net direction of rotation, resulting in a series of order-disorder switching transitions. The transport curves show abrupt jumps up or down at the transitions, which also correspond with changes in the topological order. We find similar switching transitions when both species rotate out of phase with each other. For intermediate driving frequencies, the system becomes increasingly fluid-like and the laning behavior is lost. At high frequencies, however, the system can again exhibit patterned flow when the rotation orbits become smaller than the average spacing between particles. The switching is reduced when a finite temperature is included, but even for temperatures at which the uniform equilibrium bulk system is liquid, the partially jammed state can generate local density enhancements that lead to recrystallization. We demonstrate the pattern switching behavior for systems with different screened repulsive interaction potentials.