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

The coherence length of metallic liquids, which determines viscosity, is known to display a Curie-Weiss temperature dependence; 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 clusters of atoms, or dynamical heterogeneities, which are soft spots susceptible to atomic rearrangement, whose typical size is determined by the atomic correlation length. The coherence length in the metallic liquid is thus the correlation length between dynamical heterogeneities. Our results reaffirm the idea that the coherence length is a measure of point-to-set correlations, and that local frustrations in the interatomic interactions are prominent in coherence in metallic liquids.