Non-universal critical aging scaling in three-dimensional Heisenberg antiferromagnets

TL;DR

This study numerically explores the critical aging dynamics in three-dimensional Heisenberg antiferromagnets, revealing that aging scaling exponents depend on initial conditions, challenging the notion of universality.

Contribution

It demonstrates that the aging decay exponent in critical dynamics is non-universal and depends on initial conserved field distributions, supported by hybrid simulation results.

Findings

Aging collapse exponent is universal.

Decay exponent depends on initial spin distribution.

Simulation confirms non-universality of certain critical exponents.

Abstract

We numerically investigate the stationary and non-equilibrium critical dynamics in three-dimensional isotropic Heisenberg antiferromagnets. Since the non-conserved staggered magnetization couples dynamically to the conserved magnetization density, we employ a hybrid simulation algorithm that combines reversible spin precession with relaxational Kawasaki spin exchange processes. We measure the dynamic critical exponent and identify a suitable intermediate time window to obtain the aging scaling exponents. Our results support an earlier renormalization group prediction: While the critical aging collapse exponent assumes a universal value, the associated temporal decay exponent in the two-time spin autocorrelation function depends on the initial distribution of the conserved fields; here, specifically on the width of the initial spin orientation distribution.