Depinning of a domain wall in the 2d random-field Ising model |
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Authors: | B Drossel K Dahmen |
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Institution: | (1) Department of Theoretical Physics, University of Manchester, Manchester M13 9PL, England, GB;(2) Lyman Laboratory of Physics, Harvard University, Cambridge, MA02138, USA, US |
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Abstract: | 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.
Received: 13 February 1998 / Accepted: 30 March 1998 |
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Keywords: | PACS 75 60 Ch Domain walls and domain structure - 05 70 Ln Nonequilibrium thermodynamics irreversible processes - 47 55 Lh Flows through porous media |
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