Lane formation in driven colloidal mixtures: is it continuous or discontinuous?

TL;DR

This study investigates lane formation in driven colloidal mixtures, revealing that electric field-induced lanes form continuously, while gravity-driven lanes exhibit a discontinuous transition, based on simulations and experiments.

Contribution

It demonstrates that the nature of lane formation transitions depends on the driving force type, with a novel comparison between electric and gravitational driving mechanisms.

Findings

Electric field induces continuous lane formation.

Gravity causes a discontinuous transition.

Simulations and experiments agree on the transition nature for electric driving.

Abstract

Binary mixtures of oppositely charged colloids driven by an electric field are shown to exhibit a nonequilibrium transition towards lane formation if the driving force is increased. Brownian dynamics computer simulations and real-space experiments are employed to study hysteresis effects in an order parameter measuring the extent of lane formation upon increasing and decreasing the driving force. Both from simulation and experiment, we find that lane formation due to electrical fields is continuous. However, simulations show a discontinuous transition if the driving force is gravity.