Topological Defects in ³He-A Films Following a Quench

In equilibrium, confined films of superfluid ³He-A with thickness D ≲ 10 ξ₀ have the chiral axis, ℓ, locked normal to the surface of the film (+z). There are two degenerate ground states ℓ || ± z. However, for a temperature quench, i.e. cool down through the phase transition at a finite rate, causally disconnected regions of order parameter fluctuations develop into an inhomogeneous ordered phase that hosts both vortices with winding numbers n ∈ Z and domain walls between time-reversed chiral phases. Our simulations based on a time-dependent generalization of Ginzburg-Landau theory for strong coupling ³He reveal that both vortices and domain walls are present. We report results for the formation of inequivalent chiral vortices, dynamics of vortices interacting with anti-vortices and domain walls, as well as the full counting statistics of the defects in quenched ³He, and compare the latter with recent theoretical models. We also show that the vortex density as a function of quench rate agrees with the scaling relation predicted by Kibble and Zurek.