Defect-phase-dynamics approach to statistical domain-growth problem of clock models

The idea of phase dynamics is introduced into the statistical domain-growth problem by extending the earlier work of Ohta, Jasnow, and Kawasaki [Phys. Rev. Lett. 49, 1223 (1982)]. This is combined with defect dynamics necessitated by the multivaluedness of the phase variable to study random domain growth of clock models. In two dimensions the problem is approximately reduced to that of a purely dissipative two-dimensional Coulomb gas. We predict the asymptotic t1/2 growth law, although pinning effects by defects (vertices) can complicate the behavior at shorter times. Possible extension to Potts models is briefly discussed.