J. A. N. Filipe | Searcharxiv

arXiv1995

Phase Ordering Kinetics with External Fields and Biased Initial Conditions

The late-time phase-ordering kinetics of the O(n) model for a non-conserved order parameter are considered for the case where the O(n) symmetry is broken by the initial conditions or by an external field. An approximate 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 autocorrelation function, and the density of topological defects [e.g. domain walls ($n=1$), or vortices ($n=2$)]. The results are in qualitative agreement with experiments on nematic films and related numerical simulations on the two-dimensional XY model with biased initial conditions.

cond-mat↗

arXiv1993

Gaussian Approach for Phase Ordering in Nonconserved Scalar Systems with Long-Range Interactions

We have applied the gaussian auxiliary field method introduced by Mazenko to the ordering dynamics of a non-conserved scalar system with attractive long-range interactions. This study provides a test-bed for the approach and shows some of the difficulties encountered in constructing a closed theory for the pair correlation function. The equation obtained for the equal-time two-point correlation function is studied in the limiting cases of small and large values of the scaling variable. A Porod regime at short distance and an asymptotic power-law decay at large distance are obtained. The theory, is not, however, consistent with the expected growth-law, and attempts to retrieve the correct growth lead to inconsistencies. These results indicate a failure of the gaussian assumption (at least in the form in which we use it) for this system.

cond-mat↗