Stretched exponential relaxation for growing interfaces in quenched disordered media

TL;DR

This paper investigates the relaxation dynamics of growing interfaces in quenched disordered media, revealing a two-step decay with stretched exponential behavior linked to cluster structures of pinning cells.

Contribution

It introduces a detailed analysis of relaxation in a directed percolation depinning model, highlighting the role of cluster structures and quenched noise in relaxation behavior.

Findings

Long-time tail fits stretched exponential decay.

Relaxation time diverges as a power law.

Two-step relaxation depends on cluster size and orientation.

Abstract

We study the relaxation for growing interfaces in quenched disordered media. We use a directed percolation depinning model introduced by Tang and Leschhorn for 1+1-dimensions. We define the two-time autocorrelation function of the interface height C(t',t) and its Fourier transform. These functions depend on the difference of times t-t' for long enough times, this is the steady-state regime. We find a two-step relaxation decay in this regime. The long time tail can be fitted by a stretched exponential relaxation function. The relaxation time is proportional to the characteristic distance of the clusters of pinning cells in the direction parallel to the interface and it diverges as a power law. The two-step relaxation is lost at a given wave length of the Fourier transform, which is proportional to the characteristic distance of the clusters of pinning cells in the direction perpendicular to the interface. The stretched exponential relaxation is caused by the existence of clusters of pinning cells and it is a direct consequence of the quenched noise.