Anisotropic Cage Evolution in Quasi-two-dimensional Colloidal Fluids

TL;DR

This study investigates how cages in quasi-two-dimensional colloidal fluids evolve dynamically, revealing anisotropic restructuring and region-specific particle contributions, offering insights into fluid relaxation and phase behavior.

Contribution

It provides the first experimental observation of anisotropic cage evolution in colloidal fluids and links local particle behavior to overall structural relaxation.

Findings

Cages show isotropic evolution in the lab frame but anisotropic in the displacement frame.

Particles in different regions of the cage contribute differently to persistence and relaxation.

The study offers a microscopic understanding of structural relaxation in confined colloidal fluids.

Abstract

We experimentally explore the morphological evolution of cages in quasi-two-dimensional suspensions of colloidal fluids, uncovering a complex dynamic restructuring in the fluid. Although cages display isotropic evolution in the laboratory frame, we observe a striking anisotropy when analyzed in the displacement frame of the caged particles. Moreover, our findings reveal that particles in specific but distinct regions of the cage predominantly contribute to either its persistence or relaxation. Thus, our study provides a coarse-grained microscopic picture of the structural relaxation of these fluids through cage evolution, which has broader implications for the flow and phase behavior of complex fluids in confined geometry.