Heterogeneous slow dynamics in a two dimensional doped classical antiferromagnet

TL;DR

This paper presents a classical two-dimensional doped antiferromagnet model exhibiting slow, heterogeneous dynamics and relaxation behaviors akin to supercooled liquids, without quenched disorder.

Contribution

It introduces a new lattice model demonstrating glassy dynamics in a disorder-free classical system, with detailed analysis of correlations and violations of classical relations.

Findings

Anomalous diffusion and stretched-exponential relaxation at low temperatures

Diverging relaxation times with sub-Arrhenius or Arrhenius behavior

Evidence of spatial heterogeneity and violation of Stokes-Einstein relations

Abstract

We introduce a lattice model for a classical doped two dimensional antiferromagnet which has no quenched disorder, yet displays slow dynamics similar to those observed in supercooled liquids. We calculate two-time spatial and spin correlations via Monte Carlo simulations and find that for sufficiently low temperatures, there is anomalous diffusion and stretched-exponential relaxation of spin correlations. The relaxation times associated with spin correlations and diffusion both diverge at low temperatures in a sub-Arrhenius fashion if the fit is done over a large temperature-window or an Arrhenius fashion if only low temperatures are considered. We find evidence of spatially heterogeneous dynamics, in which vacancies created by changes in occupation facilitate spin flips on neighbouring sites. We find violations of the Stokes-Einstein relation and Debye-Stokes-Einstein relation and show that the probability distributions of local spatial correlations indicate fast and slow populations of sites, and local spin correlations indicate a wide distribution of relaxation times, similar to observ ations in other glassy systems with and without quenched disorder.