Aging Exponents for Nonequilibrium Dynamics following Quenches from Critical Point

TL;DR

This study uses Monte Carlo simulations to analyze aging exponents in the nonequilibrium dynamics of the 3D Ising model after quenches from the critical point, revealing universal decay behaviors.

Contribution

It provides the first quantitative estimates of aging exponents for quenches from the critical point in 3D Ising models, including bounds and comparisons across dynamics types.

Findings

Aging exponents satisfy a theoretical bound.

Exponents are similar for conserved and nonconserved dynamics.

Results are more accurate for the 2D case.

Abstract

Via Monte Carlo simulations we study nonequilibrium dynamics in the nearest-neighbor Ising model, following quenches to points inside the ordered region of the phase diagram. With the broad objective of quantifying the nonequilibrium universality classes corresponding to spatially correlated and uncorrelated initial configurations, in this paper we present results for the decay of the order-parameter autocorrelation function for quenches from the critical point. This autocorrelation is an important probe for the aging dynamics in far-from-equilibrium systems and typically exhibits power-law scaling. From the state-of-the-art analysis of the simulation results we quantify the corresponding exponents ($\mathbf{\lambda}$) for both conserved and nonconserved (order parameter) dynamics of the model, in space dimension $d=3$. Via structural analysis we demonstrate that the exponents satisfy a bound. We also revisit the $d=2$ case to obtain more accurate results. It appears that irrespective of the dimension, $\lambda$ is same for both conserved and nonconserved dynamics.