Roughness of a Tilted Anharmonic String at Depinning

TL;DR

This study investigates the roughness of a tilted anharmonic string at the depinning threshold, revealing a transition to the quenched KPZ universality class due to anharmonic effects.

Contribution

It demonstrates that anharmonic elastic energy causes the model to transition to the quenched KPZ universality class at depinning.

Findings

The roughness at depinning follows finite size scaling.

Tilted anharmonic strings exhibit quenched KPZ universality.

The transition aligns with recent theoretical predictions.

Abstract

We consider the discretized model of a driven string with an anharmonic elastic energy, in a two dimensional random potential, as introduced by Rosso and Krauth. Using finite size scaling, we numerically compute the roughness of the string in a uniform applied force at the critical depinning threshold. By considering a string with a net average tilt, we demonstrate that the anharmonic elastic energy crosses the model over to the quenched KPZ universality class, in agreement with recent theoretical predictions.