https://doi.org/10.1007/s100510050339
Depinning of a domain wall in the 2d random-field Ising model*
1
Department of Theoretical Physics,
University of Manchester,
Manchester M13 9PL, England
2
Lyman Laboratory of Physics,
Harvard University,
Cambridge, MA02138, USA
Corresponding authors: a drossel@a13.ph.man.ac.uk - b dahmen@cmt.harvard.edu
Received:
13
February
1998
Accepted:
30
March
1998
Published online: 15 June 1998
We report studies of the behaviour of a single driven domain wall in the
2-dimensional non-equilibrium zero temperature random-field Ising model,
closely above the depinning threshold. It is found that even for very
weak disorder, the domain wall moves through the system in percolative
fashion. At depinning, the fraction of spins that are flipped by the
proceeding avalanche vanishes with the same exponent
as the infinite percolation cluster in percolation theory.
With decreasing disorder strength, however, the size of the critical
region decreases. Our
numerical simulation data appear to reflect a crossover behaviour
to an exponent
at zero disorder strength.
The conclusions of this paper strongly rely on analytical arguments.
A scaling theory in
terms of the disorder strength and the magnetic field is presented
that gives the values of all critical exponent except for one, the
value of which is estimated from scaling arguments.
PACS: 75.60.Ch – Domain walls and domain structure / 05.70.Ln – Nonequilibrium thermodynamics, irreversible processes / 47.55.Lh – Flows through porous media
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998