Polar core vortex dynamics in disc-trapped homogeneous spin-1 Bose-Einstein condensates

We study the superfluid spin vortices in the easy-plane phase of an atomic spin-1 Bose-Einstein condensate confined in a two-dimensional disc potential. Numerical simulations in the presence of both linear and quadratic magnetic Zeeman fields reveal the unusual phenomenology of single and pairs of polar core vortices. Vortex pairs with opposing winding numbers either move towards or away from each other, depending on their initial position, while same-sign vortices move apart. We quantify the vortices dynamics in terms of the spinor parameter space for realistic experimental parameters. Spiral vortex dynamics are obtained for same-sign pairs in the presence of a finite axial magnetization.