# Attraction Controls the Inversion of Order by Disorder

## TL;DR

This paper demonstrates that attractive interactions in colloidal systems can reverse the typical order-disorder effects caused by fluctuations, influencing the stable ground state configurations through local packing and geometric considerations.

## Contribution

It reveals how attraction in interparticle interactions determines the ordering in frustrated colloidal systems, linking geometric mechanisms to entropy and enabling design of self-assembled structures.

## Key findings

- Attraction reverses the fluctuation-driven ordering in colloidal monolayers.
- Bent stripes are stable in colloids, while straight stripes are favored in Ising models.
- Attraction influences local packing, affecting the system's ground state.

## Abstract

We show how including attraction in interparticle interactions reverses the effect of fluctuations in ordering of a prototypical artificial frustrated system. Buckled colloidal monolayers exhibit the same ground state as the Ising antiferromagnet on a deformable triangular lattice, but it is unclear if ordering in the two systems is driven by the same geometric mechanism. By a real-space expansion we find that for buckled colloids bent stripes constitute the stable phase, whereas in the Ising antiferromagnet straight stripes are favored. For generic pair potentials we show that attraction governs this selection mechanism, in a manner that is linked to local packing considerations. This supports the geometric origin of entropy in jammed sphere packings and provides a tool for designing self-assembled colloidal structures.