Crossover from three- to six-fold symmetry of colloidal aggregates in circular traps

TL;DR

This study investigates how colloidal particles confined in circular traps transition between three- and six-fold symmetries, revealing a dynamic interplay influenced by trap width and external modulation.

Contribution

It demonstrates the symmetry crossover in colloidal aggregates due to competing isotropic and anisotropic interactions within circular traps.

Findings

Core-shell structures with mixed symmetry form at intermediate trap widths

Symmetry can dynamically change with trap width modulation

Structures depend on the interplay between interparticle and external potentials

Abstract

At sufficiently low temperatures and high densities, repulsive spherical particles in two-dimensions (2d) form close-packed structures with six-fold symmetry. By contrast, when the interparticle interaction has an attractive anisotropic component, the structure may exhibit the symmetry of the interaction. We consider a suspension of spherical particles interacting through an isotropic repulsive potential and a three-fold symmetric attractive interaction, confined in circular potential traps in 2d. We find that, due to the competition between the interparticle and the external potentials, the particles self-organize into structures with three- or six-fold symmetry, depending on the width of the traps. For intermediate trap widths, a core-shell structure is formed, where the core has six-fold symmetry and the shell is three-fold symmetric. When the width of the trap changes periodically in time, the symmetry of the colloidal structure also changes, but it does not necessarily follow that of the corresponding static trap.