Orientational Dynamics of Fluctuating Dipolar Particles Assembled in a Mesoscopic Colloidal Ribbon

TL;DR

This study combines experiments and theory to analyze how magnetic microellipsoids in a colloidal ribbon fluctuate in orientation under magnetic fields, providing insights into their stability and dynamics.

Contribution

It introduces a combined experimental and theoretical approach to describe orientational fluctuations of dipolar particles in a ribbon structure under magnetic fields.

Findings

Experimental data agree with the theoretical model across various field strengths.

Orientational fluctuations can be controlled via in-plane magnetic fields.

The model predicts the distribution of angular configurations based on field strength.

Abstract

We combine experiments and theory to investigate the dynamics and orientational fluctuations of ferromagnetic microellipsoids that form a ribbon-like structure due to attractive dipolar forces. When assembled in the ribbon, the ellipsoids displays orientational thermal uctuations with an amplitude that can be controlled via application of an in-plane magnetic field. We use video microscopy to investigate the orientational dynamics in real time/space. Theoretical arguments are used to derive an analytical expression that describes how the distribution of the different angular configurations depends on the strength of the applied field. The experimental data are in good agreement with the developed model for all the range of field parameters explored. Understanding the role of uctuations in chains composed of dipolar particles is important not only from a fundamental point of view, but it may also help understanding the stability of such structures against thermal noise, which is relevant in micro uidics and lab-on-a-chip applications.