Hamburg 2001 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 46: Poster
DY 46.3: Poster
Donnerstag, 29. März 2001, 15:45–18:15, Foyer S\ 3
Interface motion in disordered media — •L. Roters, S. Lübeck, and K.D. Usadel — Theoretische Physik, Gerhard-Mercator-Universität, 47048 Duisburg
We numerically investigate the dynamics of driven interfaces in the
random-field Ising model.
At zero temperature the system displays a continuous phase transition
from a pinned to a moving interface at a certain driving field
H c.
Approaching H c from above the interface
velocity v vanishes according to v ∼ (H−H c)β
and is zero below the critical threshold.
With thermal fluctuations the interface moves for any finite value of
the driving field.
Our analyses reveal that at the transition point the interface
velocity increases according v ∼ T1/δ at
H=H c.
We determine the exponents β and δ in a hypercube of
various dimensions d=3,4,5,6.
In the five dimensional case we find logarithmic corrections to
the power-law behavior.
Our results are, therefore, consistent with the assumption that five
is the upper critical dimension of the depinning transition in the RFIM.
Furthermore, we investigate the depinning transition in thin films
and observe a crossover from three- to two-dimensional scaling
behavior.
This crossover is caused by the interplay between a diverging
correlation length and the finite film thickness.