Coupling between particle shape and long-range interaction in the high-density regime

TL;DR

This study experimentally investigates how particle shape influences long-range interaction-driven structure formation in high-density regimes, revealing distinct coupling modes for squares and triangles.

Contribution

It uncovers the coupling mechanisms between particle shape and long-range interactions, demonstrating shape-dependent structural transitions in high-density polygon systems.

Findings

Squares induce a hexagonal-to-rhombic transition due to lattice deformation.

Triangles cause an order-to-disorder transition from geometric frustration.

Different coupling modes affect the internal roughness and relaxation dynamics.

Abstract

By using long-range interacting polygons, we experimentally probe the coupling between particle shape and long-range interaction. For two typical space-filling polygons, square and triangle, we find two types of coupling modes that predominantly control the structure formation. Specifically, the rotational ordering of squares brings a lattice deformation that produces a hexagonal-to-rhombic transition in the high-density regime, whereas the alignment of triangles introduces a large geometric frustration that causes an order-to-disorder transition. Moreover, the two coupling modes lead to small and large "internal roughness" of the two systems, and thus predominantly control their structure relaxations. Our study thus provides a physical picture to the coupling between long-range interaction effect and short-range shape effect in the high-density regime unexplored before.