PHASE-ORDERING KINETICS WITH EXTERNAL FIELDS AND BIASED INITIAL CONDITIONS

The late-time phase-ordering kinetics of the O(n) model for a nonconse rved order parameter are considered for the case where the O(n) symmet ry is broken by the initial conditions or by an external field. An app roximate theoretical approach, based on a ''Gaussian closure'' scheme, is developed, and results are obtained for the time dependence of the mean order parameter, the pair correlation function, the autocorrelat ion function, and the density of topological defects [e.g., domain wal ls (n = 1), or vortices (n = 2)]. The results are in qualitative agree ment with experiments on nematic films and related numerical simulatio ns on the two-dimensional XY model with biased initial conditions.