Regensburg 2000 – wissenschaftliches Programm

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AM: Magnetismus

AM 12: Mikromagnetismus, Magnetisierungsprozesse und Domänenstrukturen II

AM 12.3: Vortrag

Dienstag, 28. März 2000, 14:45–15:00, H22

Creep motion in a random-field Ising model — •Lars Roters, Sven Lübeck, and K. D. Usadel — Theoretische Physik, Gerhard-Mercator-Universität, 47048 Duisburg

We investigate the motion of magnetic domain walls in disordered systems in the limit of strong uniaxial anisotropy by means of Monte Carlo simulations. Without thermal fluctuations the interface will remain in a metastable pinned state if the driving field does not exceed some critical value. For finite temperatures the energy needed to overcome metastable states can be provided by thermal fluctuations.

In our investigations we consider the interface motion in a random-field Ising system in the creep regime which occurs for low temperature and small driving fields. In this regime the dependence of the interface velocity on the temperature is given by an Arrhenius law whose energy barrier characterizes the energy needed to overcome metastable states. The dependence of the energy barrier on the driving field and the strength of disorder is investigated.