Features Of Phase Ordering In (2+1)-Dimensional O(3) Models

Numerical simulations of phase ordering under dissipative dynamics in a (2 + 1)-dimensional 3-vector model with O(3) symmetry are reported. The energy functional includes terms which stabilize the size of extended topological defects. They emerge at the end of the coarsening process as particle- or antiparticle-like structures floating in the globally aligned vacuum. Approximate power-law growth of disoriented domains (with an exponent near 0.4) is found to be rather insensitive to the size of the defects. An optional filter for conservation of winding number allows us to study phase ordering in a high defect-density environment which leads to large clusters of particles surrounded by the aligned field.