Simulation Of Domain-Wall Dynamics In The 2d Anisotropic Ising-Model

Abstract

The authors first show that the movement of a domain wall in a highly anisotropic Ising model of spins in two dimensions can be mapped to a random walk movement of labelled walkers in one dimension. This movement is correlated in the sense that the transition probability of a given walker, labelled i, depends upon the current positions of its labelled neighbours (i-1 and i+1). A Monte Carlo simulation of the walk for various numbers of walkers (up to a maximum of 50) and for quite long times (up to a maximum of 25*104 Monte Carlo steps) yields useful and interesting information about the dynamics. They verify that (i) the centre of mass of the walkers executes an unbiased random walk for all times starting from the lowest times; and (ii) the moment of inertia of the walkers asymptotically reaches a constant value which scales with the number of walkers. They also discuss the relation of this work to the dynamics in the 2D Ising model, identifying phi with the dynamical exponent z. The random walk equivalence also provides a geometrical interpretation of the known results for the solid-on-solid model.