  Dynamics of a vortex dipole in a spin-1 Bose-Einstein condensate in which
magnetic phases are spatially distributed is investigated. When a vortex dipole
travels from the ferromagnetic phase to the polar phase, or vice versa, it
penetrates the phase boundary and transforms into one of the various spin
vortex dipoles, such as a leapfrogging ferromagnetic-core vortex dipole and a
half-quantum vortex dipole. Topological connections of spin wave functions
across the phase boundary are discussed.
