Fast and rewritable colloidal assembly via field synchronized particle swapping

TL;DR

This paper introduces a method for creating reconfigurable colloidal crystals by controlling particle defect motion with an external magnetic field, enabling fast, reversible, and programmable assembly and disassembly.

Contribution

It presents a novel magnetic field-driven particle swapping technique for dynamic and rewritable colloidal assembly on a patterned magnetic substrate.

Findings

Demonstrated controlled particle transport via defect propagation.

Achieved reversible reconfiguration of colloidal structures.

Enabled programmable assembly with magnetic field modulation.

Abstract

We report a technique to realize reconfigurable colloidal crystals by using the controlled motion of particle defects above an externally modulated magnetic substrate. The transport of particles is induced by applying a uniform rotating magnetic field to a ferrite garnet film characterized by a periodic lattice of magnetic bubbles. For filling factor larger than one colloid per bubble domain, the particle current arises from propagating defects where particles synchronously exchange their position when passing from one occupied domain to the next. The amplitude of an applied alternating magnetic field can be used to displace the excess particles via a swapping mechanism, or to mobilize the entire colloidal system at a predefined speed.