Hyperuniformity near jamming transition over a wide range of bidispersity

TL;DR

This study numerically examines hyperuniformity in two-dimensional bidisperse jammed packings, revealing a consistent exponent near 0.6-0.7 across various size ratios, contrasting with three-dimensional systems.

Contribution

It applies a novel high-precision method to determine hyperuniformity exponents in 2D bidisperse systems, highlighting differences from 3D behaviors and effects of polydispersity.

Findings

Hyperuniformity characterized by $S(q) o 0$ as $q o 0$ with $eta ext{~} 0.6 ext{--}0.7$.

Exponent $eta$ remains consistent across size ratios, except in monodisperse cases.

Contrasts with 3D systems where $eta$ is approximately 1.

Abstract

We numerically investigate hyperuniformity in two-dimensional frictionless jammed packings of bidisperse systems. Hyperuniformity is characterized by the suppression of density fluctuations at large length scales, and the structure factor asymptotically vanishes in the small-wavenumber limit as $S(q) \propto q^{\alpha}$, where $\alpha > 0$. It is well known that jammed configurations exhibit hyperuniformity over a wide range of wavenumbers windows, down to $q^{\ast}\sigma \approx 0.2$, where $\sigma$ is the particle diameter. In two dimensions, we find that the exponent $\alpha$ is approximately $0.6\text{--}0.7$. This contrasts with the reported value of $\alpha = 1$ for three-dimensional systems. We employ an advanced method recently introduced by Rissone \textit{et al.} \href{https://link.aps.org/doi/10.1103/PhysRevLett.127.038001}{[Phys. Rev. Lett. {\bf 127}, 038001 (2021)]}, originally developed for monodisperse and three-dimensional systems, to determine $\alpha$ with high precision. This exponent is found to be unchanged for all size ratios between small and large particles, except in the monodisperse case, where the system crystallizes.