Novel domain growth law in random magnets

Abstract

We investigate the kinetics of domain growth in Ising magnets where a fraction 1 - p of the magnetic atoms or ions (spins) are randomly substituted by non-magnetic impurities. We argue that close to the percolation threshold p_c, the statistical self-similarity of the underlying structure gives rise to a novel crossover in the growth law. We propose a method to detect any evidence of this new prediction from the kinetics of domain growth in the dilute Ising model (DIM) during intermediate time scales by carrying out Monte Carlo simulations not at p = p_c but at slightly higher spin concentrations. We analyze the results of our extensive Monte Carlo simulation of the strongly diluted two-dimensional Ising model and find the growth to be consistent with the proposed scenario. We also compare our observations with those in the recent experiments on the kinetics of ordering in Rb₂Co_pMg_1-pF₄.