Nonequilibrium critical dynamics in inhomogeneous systems

TL;DR

This paper investigates the nonequilibrium critical dynamics at surfaces and defects in inhomogeneous systems, revealing two distinct short-time dynamical behaviors depending on static correlation decay, with implications for real ferromagnets.

Contribution

It identifies and characterizes two types of short-time dynamics in inhomogeneous critical systems, including a universal cluster dissolution scenario observable at surfaces.

Findings

Short-time dynamics depend on static correlation decay rate.

Cluster dissolution leads to stationary, stretched exponential correlations.

Surface dynamics in 3D Ising model exhibit cluster dissolution behavior.

Abstract

We study nonequilibrium dynamical properties of inhomogeneous systems, in particular at a free surface or at a defect plane. Thereby we consider nonconserved (model-A) dynamics of a system which is prepared in the high-temperature phase and quenched into the critical point. Using Monte Carlo simulations we measure single spin relaxation and autocorrelations, as well as manifold autocorrelations and persistence. We show that, depending on the decay of critical static correlations, the short time dynamics can be of two kinds. For slow decay of local correlations the usual domain growth process takes place with non-stationary and algebraic dynamical correlations. If, however, the local correlations decay sufficiently rapidly we have the so called cluster dissolution scenario, in which case short time dynamical correlations are stationary and have a universal stretched exponential form. This latter phenomenon takes place in the surface of the three-dimensional Ising model and should be observable in real ferromagnets.