Quantum droplets with magnetic vortices in spinor dipolar Bose-Einstein condensates

Motivated by the recent experimental realization of a Bose-Einstein condensate (BEC) of europium atoms, we investigate the self-bound droplet state for a dipolar BEC with spin degrees of freedom. Under a sufficiently weak magnetic field, the droplet has a torus shape with circulating spin vectors, which is referred to as a magnetic vortex. The ground state transforms from a torus to a cigar shape through bistability with increasing magnetic field. Dynamical change of the magnetic field causes the torus to rotate due to the Einstein–de Haas effect. The magnetic vortices form a supersolid in a confined system. Published by the American Physical Society 2024