Topological edge flows drive macroscopic re-organization in magnetic colloids

TL;DR

This paper introduces a topological framework to understand how edge flows in magnetic colloids drive large-scale reorganization, revealing protected flows and shear stress effects that influence cluster dynamics.

Contribution

The study presents a novel topological approach to predict protected edge flows in magnetic colloids, linking topology to non-equilibrium dynamics and system reorganization.

Findings

Edge flows are topologically protected despite thermal motion.

Shear stress from edge flows causes global rotation of clusters.

Experimental validation with super-paramagnetic colloids confirms theoretical predictions.

Abstract

Magnetic colloids can be driven with time-varying fields to form clusters and voids that re-organize over vastly different timescales. However, the driving force behind these non-equilibrium dynamics is not well-understood. Here, we introduce a topological framework that predicts protected edge flows despite strong thermal motion. Notably, these edge flows produce shear stress that creates global rotation of clusters but not of voids. We verify this theory experimentally using micron-sized super-paramagnetic colloids to demonstrate these emergent physical predictions and show how they drive system re-organization differentially at long timescales. Our results elucidate fundamental principles that shape and control non-equilibrium colloidal aggregates.