Mean-field model for the Curie-Weiss temperature dependence of coherence length in metallic liquids

TL;DR

This paper introduces a mean-field pseudospin model to explain the Curie-Weiss temperature dependence of the coherence length in metallic liquids, linking atomic interactions and dynamical heterogeneities.

Contribution

It presents a novel Ising-spin based mean-field model that captures the temperature dependence of coherence length in metallic liquids, emphasizing local frustrations and heterogeneities.

Findings

Coherence length diverges at a negative temperature with a critical exponent of one.

The model links the coherence length to point-to-set correlations.

Local frustrations significantly influence the medium-range order in metallic liquids.

Abstract

The coherence length of the medium-range order (MRO) in metallic liquids is known to display a Curie-Weiss temperature dependence; its inverse is linearly related to temperature, and when extrapolated from temperatures above the glass transition, the coherence length diverges at a negative temperature with a critical exponent of unity. We propose a mean-field pseudospin model that explains this behavior. Specifically, we model the atoms and their local environment as Ising spins with antiferromagnetic exchange interactions. We further superimpose an exchange interaction between dynamical heterogeneities, or clusters of atoms undergoing cooperative motion. The coherence length in the metallic liquid is thus the correlation length between dynamical heterogeneities. Our results reaffirm the idea that the MRO coherence length is a measure of point-to-set correlations, and that local frustrations in the interatomic interactions are prominent in metallic liquids.