Lane reduction in driven 2d-colloidal systems through microchannels

TL;DR

This study investigates how gravitationally driven colloidal particles in microchannels undergo lane reduction and phase transitions, combining experimental observations with Brownian dynamics simulations to understand the underlying mechanisms.

Contribution

It introduces a detailed analysis of lane reduction and phase transitions in driven colloidal systems using combined experimental and simulation approaches.

Findings

Lane reduction occurs due to density gradients and particle reconfiguration.

A local melting and crystallization process accompanies lane reduction.

Experimental results are supported by Brownian dynamics simulations.

Abstract

The transport behavior of a system of gravitationally driven colloidal particles is investigated. The particle interactions are determined by the superparamagnetic behavior of the particles. They can thus be arranged in a crystalline order by application of an external magnetic field. Therefore the motion of the particles through a narrow channel occurs in well-defined lanes. The arrangement of the particles is perturbed by diffusion and the motion induced by gravity. Due to these combined influences a density gradient forms along the direction of motion of the particles. A reconfiguration of the crystal is observed leading to a reduction of the number of lanes. In the course of the lane reduction transition a local melting of the quasi-crystalline phase to a disordered phase and a subsequent crystallization along the motion of the particles is observed. This transition is characterized experimentally and using Brownian dynamics (BD) simulations.