Order-Disorder Transitions and Thermal Pathways in Frustrated 2D Colloidal Crystals

TL;DR

This study uses molecular dynamics simulations to investigate how different 2D colloidal crystal phases melt and recrystallize, revealing the influence of lattice geometry and frustration on phase transition pathways.

Contribution

It provides new insights into the melting and freezing behaviors of frustrated 2D colloidal crystals with multiple solid phases, highlighting non-universal pathways.

Findings

LDT and kagome phases melt via first-order transitions.

Only the LDT phase recrystallizes smoothly.

Stripe phase shows continuous and reversible transformation.

Abstract

We employ extensive NPT molecular dynamics simulations to explore the thermal transitions of two-dimensional colloidal crystals interacting via a core-softened potential with competing length scales. The system stabilizes three distinct solid phases, namely low-density triangular (LDT), stripe, and kagome, which exhibit markedly different responses to heating and cooling. Our simulations reveal that the LDT and kagome phases melt via first-order transitions, but only the former recrystallizes smoothly. The kagome phase displays strong hysteresis and metastability, while the stripe phase undergoes a continuous and nearly reversible transformation. These results highlight the role of lattice geometry and frustration in shaping non-universal melting and freezing pathways in 2D soft matter.