Dynamics of vortex defect formation in two-dimensional Coulomb crystals

We study the nonequilibrium dynamics of two-dimensional planar ion Coulomb crystals undergoing a structural buckling transition to a three-plane configuration, driven by a reduction of the transverse confining frequency. This phase transition can be theoretically modeled using a mapping to a two-dimensional Ginzburg-Landau theory with a complex order parameter field. We demonstrate that finite rate quenches result in the creation of stable topological vortices, which are localized point regions around which the phase of the order parameter field winds a multiple of 2π. The density of the defects as a function of quench rate is investigated using molecular dynamics simulations, and its scaling is shown to be consistent with Kibble-Zurek theory of defect formation. Following the quench, the annihilation of vortex and antivortex pairs results in the relaxation of defect density that follows a diffusive scaling with a logarithmic correction. This paper highlights the potential for investigating complex nonequilibrium statistical physics of topological defects in an experimentally accessible ion trap setting.