J. Phys. IV France 12 (2002) Pr9-275
DOI: 10.1051/jp4:20020414

Domain walls in random media driven by AC fields

A. Glatz¹, T. Nattermann² and V. Pokr vsky<sup>3, 4

1</sup>  Institut fur Theoretische Physik, Universität zu Köln, Zulpicher Str. 77, 50937 Koln, Germany
²  LPMMH, École Supérieure de Physique et de Chimie Industrielles, 75231 Paris cedex 05, France
³  Department of Physics, Texas A&M University, College Station, Texas 77843-4242, U.S.A.
⁴  Landau Institute for Theoretical Physics, Chernogolovka, Moscow District 142432, Russia

Abstract
The viscous motion of an interface driven by an ac external field of frequency 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 . 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.

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