Aging in coarsening diluted ferromagnets

TL;DR

This study investigates aging and non-equilibrium relaxation in a two-dimensional diluted ferromagnetic model, revealing simple aging behavior when accounting for non-algebraic growth of correlations, contrasting earlier superaging assumptions.

Contribution

It provides a comprehensive numerical analysis of aging in disordered ferromagnets, highlighting non-algebraic growth and confirming simple aging behavior in various scaling functions.

Findings

Deviations from algebraic growth in correlation length observed

Simple aging behavior confirmed when non-algebraic growth is considered

Agreement with simple aging in space-time correlation and response functions

Abstract

We comprehensively study non-equilibrium relaxation and aging processes in the two-dimensional random-site Ising model through numerical simulations. We discuss the dynamical correlation length as well as scaling functions of various two-times quantities as a function of temperature and of the degree of dilution. For already modest values of the dynamical correlation length $L$ deviations from a simple algebraic growth, $L(t) \sim t^{1/z}$, are observed. When taking this non-algebraic growth properly into account, a simple aging behavior of the autocorrelation function is found. This is in stark contrast to earlier studies where, based on the assumption of algebraic growth, a superaging scenario was postulated for the autocorrelation function in disordered ferromagnets. We also study the scaling behavior of the space-time correlation as well as of the time integrated linear response and find again agreement with simple aging. Finally, we briefly discuss the possibility of superuniversality in the scaling properties of space- and time-dependent quantities.