UNIVERSALITY OF ORDERING DYNAMICS IN CONSERVED MULTICOMPONENT SYSTEMS

A comparative study is performed of the ordering dynamics and spinodal decomposition processes in two-dimensional two-state and three-state ferromagnetic Potts models with conserved order parameter. The models are investigated by Monte Carlo quenching simulations on both square a nd triangular lattices and the evolving order is studied via the exces s energy, the domain-size distribution function, and the density of is olated diffusing particles, which facilitate the coarsening process. T he growth law that describes the time-evolution of the linear length s cale, R (t), of the ordered domains is found at late stages to be alge braic, R (t) approximately t(n), with the Lifshitz-Slyozov value of th e exponent, n congruent-to 1/3,, for both two- and and three-component order parameters. The domain-size distribution function is found to o bey dynamical scaling. The results suggest that, similar to the case o f nonconserved order parameter, there is a single universality class d escribing the cases of conserved order parameter independent of the nu mber of components of the order parameter. In the asymptotic regime, t he topological difference in the domain-boundary network between the v ertex-free two-state model and the vertex-generating three-state model does not affect the growth exponents but only the nonuniversal amplit udes. Details are revealed of the ordering mechanism controlled by dif fusional processes involving broken Potts bonds and isolated Potts spi ns. A transient regime can be identified as one where broken Potts bon ds in the two-state model and broken Potts bonds (isolated Potts) spin s in the three-state model diffuse along the domain boundaries and an asymptotic late-stage regime where isolated Potts spins perform a long -range diffusive process within and across the domains.