Giant vortex in a fast rotating holographic superfluid

In a holographic superfluid disk, when the rotational velocity is large enough, we find that a giant vortex will form in the center of the system by merging several single charged vortices at some specific rotational velocity with a phase stratification phenomenon for the order parameter. The formation of a giant vortex can be explained, as there is not enough space for a standard vortex lattice. If we keep increasing the rotational velocity, the giant vortex will disappear and there will be an appearance of a superfluid ring. In the giant vortex region, the number of vortices measured from winding number and rotational velocity always satisfies the linear Feynman relation. However, when the superfluid ring starts to appear, the number of vortices in the disk will decrease although the rotational velocity is increasing, while most of the order parameter is suppressed.