Lane formation in a system of dipolar microswimmers

TL;DR

This study uses Brownian Dynamics simulations to explore how dipolar microswimmers self-organize into lanes, revealing unique lane structures and conditions driven by anisotropic interactions in a 2D system.

Contribution

It uncovers the formation of complex laned states with internal structures in dipolar microswimmers, highlighting the role of anisotropic interactions and interaction strength windows.

Findings

Lanes have complex internal structures like chains or clusters.

Laning occurs only within specific interaction strength ranges.

Phase separation and force balance explain the observed structures.

Abstract

Using Brownian Dynamics (BD) simulations we investigate the non-equilibrium structure formation of a two-dimensional (2D) binary system of dipolar colloids propelling in opposite directions. Despite of a pronounced tendency for chain formation, the system displays a transition towards a laned state reminiscent of lane formation in systems with isotropic repulsive interactions. However, the anisotropic dipolar interactions induce novel features: First, the lanes have themselves a complex internal structure characterized by chains or clusters. Second, laning occurs only in a window of interaction strengths. We interprete our findings by a phase separation process and simple force balance arguments.