Domain Wall Depinning in Random Media by AC Fields

TL;DR

This paper investigates how an oscillating external field influences the depinning transition of an interface in a random medium, revealing a smeared transition with double hysteresis absent in static conditions.

Contribution

It introduces the first analysis of viscous interface motion under AC fields in random media, explaining hysteresis features via scaling and renormalization group methods.

Findings

Velocity shows smeared depinning transition with double hysteresis

Hysteresis characteristics depend on depinning threshold and critical exponents

Analysis applies to low-frequency limit, linking to adiabatic case

Abstract

The viscous motion of an interface driven by an ac external field of frequency omega_0 in a random medium is considered here for the first time. The velocity exhibits a smeared depinning transition showing a double hysteresis which is absent in the adiabatic case omega_0 --> 0. Using scaling arguments and an approximate renormalization group calculation we explain the main characteristics of the hysteresis loop. In the low frequency limit these can be expressed in terms of the depinning threshold and the critical exponents of the adiabatic case.