Vortex competition in a rotating two-component dipolar Bose-Einstein condensate

We study a harmonically trapped highly oblate two-component Bose-Einstein condensate, which consists of both dipolar and scalar bosonic atoms. When the dipoles are polarized along the symmetry axis of the trap, the dipolar atoms’ density exhibits a flat-disk regime at the trap center. It is found that the dipolar component is easier to induce the first vortex when the trap is rotating about the symmetry axis, if the long-range dipolar interactions dominate over the contact interactions, and vice versa. Vortex lattices with the compensating triangular, square, and stripe structures can be formed respectively under rapid rotation. When the dipoles are polarized perpendicular to the rotation axis, the two components are generically phase separated into a kernel-shell structure due to the anisotropic dipole-dipole interactions. While the giant-hole states are induced under slow rotation, the compensating stripe vortex structures are stabilized under fast rotation. In particular, a stripe-splitting structure is found to be competing with the stripe ones. These features are expected to be observed in the mixture of ⁵²Cr atoms in the two different spin states.