Fluctuating Topological Defects in 2D Liquids: Heterogeneous Motion and Noise

TL;DR

This study investigates defect dynamics in 2D liquids, revealing temperature-dependent noise signatures and heterogeneous defect motion linked to defect structures, using simulations with different interaction ranges.

Contribution

It demonstrates the temperature-dependent transition from 1/f noise to white noise in defect fluctuations and links defect structures to particle motion heterogeneity in 2D liquids.

Findings

1/f noise appears near the solid-liquid transition

Defects form string-like structures at certain temperatures

Heterogeneous motion correlates with defect structures

Abstract

We measure the defect density as a function of time at different temperatures in simulations of a two dimensional system of interacting particles. Just above the solid to liquid transition temperature, the power spectrum of the defect fluctuations shows a 1/f signature, which crosses over to a white noise signature at higher temperatures. When 1/f noise is present, the 5-7 defects predominately form string like structures, and the particle trajectories show a 1D correlated motion that follows the defect strings. At higher temperatures this heterogeneous motion is lost. We demonstrate this heterogeneity both in systems interacting with a short ranged screened Coulomb interaction, as well as in systems with a long range logarithmic interaction between the particles.