Vortices in a rotating two-component Bose–Einstein condensate with tunable interactions and harmonic potential

•Different vortex structures are obtained within the full parameter space.•Effects of system parameters on the ground state structure are discussed.•Phase transition between different vortex structures is also examined.•Present one possible way to obtain the rotating droplet structure.•Provide many possibilities to manipulate vortex in two-component BEC.

We consider a pair of coupled nonlinear Schrödinger equations modeling a rotating two-component Bose–Einstein condensate with tunable interactions and harmonic potential, with emphasis on the structure of vortex states by varying the strength of inter-component interaction, rotational frequency, and the aspect ratio of the harmonic potential. Our results show that the inter-component interaction greatly enhances the effect of rotation. For the case of isotropic harmonic potential and small inter-component interaction, the initial vortex structure remains unchanged. As the ratio of inter- to intra-component interactions increases, each component undergoes a transition from a vortex lattice (vortex line) in an isotropic (anisotropic) harmonic potential to an alternatively arranged stripe pattern, and eventually to the interwoven “serpentine” vortex sheets. Moreover, in the case of anisotropic harmonic potential the system can develop to a rotating droplet structure.