Roughening of an interface in a system with surface or bulk disorder

TL;DR

This study investigates how surface and bulk disorder affect the roughening behavior of interfaces in a 2D Ising model, revealing complex crossover patterns in the structure factor across different disorder regimes.

Contribution

It provides a numerical analysis of interface roughening in disordered 2D Ising models, highlighting crossover behaviors between surface and bulk disorder effects.

Findings

Rich crossover patterns in the structure factor at different wavevectors

Identification of a second crossover in the random field model from surface to bulk disorder behavior

Distinct roughening behaviors depending on the type of disorder present

Abstract

We study numerically the roughening properties of an interface in a two-dimensional Ising model with either random bonds or random fields, which are representative of universality classes where disorder acts only on the interface or also away from it, in the bulk. The dynamical structure factor shows a rich crossover pattern from the form of a pure system at large wavevectors $k$, to a different behavior, typical of the kind of disorder, at smaller $k$'s. For the random field model a second crossover is observed from the typical behavior of a system where disorder is only effective on the surface, as the random bond model, to the truly large scale behavior, where bulk-disorder is important, that is observed at the smallest wavevectors.