  We consider the formation of order in a quasi-two-dimensional (quasi-2D)
anti-ferromagnetic spin-1 condensate quenched from an easy-axis (EA) to an
easy-plane (EP) nematic phase. We define the relevant order parameter to
quantify the spin-nematic degrees of freedom and study the evolution of the
spin-nematic and superfluid order during the coarsening dynamics using
numerical simulations. We observe dynamical scaling in the late time dynamics
with both types of order extending across the system with a diffusive growth
law. We identify half-quantum vortices (HQVs) as the relevant topological
defects of the ordering dynamics, and demonstrate that the growth of both types
of order is determined by the mutual annihilation of these vortices.
