We investigate a model for randomly layered magnets, viz. a three-dimensionalIsing model with planar defects. The magnetic phase transition in this systemis smeared because static long-range order can develop on isolated rare spatialregions. Here, we report large-scale kinetic Monte Carlo simulations of thedynamical behavior close to the smeared phase transition which we characterizeby the spin (time) autocorrelation function. In the paramagnetic phase, itsbehavior is dominated by Griffiths effects similar to those in magnets withpoint defects. In the tail region of the smeared transition the dynamics iseven slower: the autocorrelation function decays like a stretched exponentialat intermediate times before approaching the exponentially small asymptoticvalue following a power law at late times. Our Monte-Carlo results are in goodagreement with recent theoretical predictions based on optimal fluctuationtheory.
展开▼
