Slow dynamics at the smeared phase transition of randomly layered magnets

TL;DR

This paper studies the slow dynamical behavior near the smeared phase transition in randomly layered Ising magnets using large-scale Monte Carlo simulations, revealing stretched exponential decay and agreement with theoretical predictions.

Contribution

It provides the first large-scale simulation analysis of dynamical behavior near smeared phase transitions in layered magnets, confirming theoretical models.

Findings

Autocorrelation decays as stretched exponential at intermediate times.

Late-time decay follows a power law.

Results agree with optimal fluctuation theory predictions.

Abstract

We investigate a model for randomly layered magnets, viz. a three-dimensional Ising model with planar defects. The magnetic phase transition in this system is smeared because static long-range order can develop on isolated rare spatial regions. Here, we report large-scale kinetic Monte Carlo simulations of the dynamical behavior close to the smeared phase transition which we characterize by the spin (time) autocorrelation function. In the paramagnetic phase, its behavior is dominated by Griffiths effects similar to those in magnets with point defects. In the tail region of the smeared transition the dynamics is even slower: the autocorrelation function decays like a stretched exponential at intermediate times before approaching the exponentially small asymptotic value following a power law at late times. Our Monte-Carlo results are in good agreement with recent theoretical predictions based on optimal fluctuation theory.