Miscibility in coupled dipolar and non-dipolar Bose-Einstein condensates

Abstract

We perform a full three-dimensional study on miscible-immiscible conditions for coupled dipolar and non-dipolar Bose-Einstein condensates (BEC), confined in anisotropic traps. In view of recent experimental studies, our focus was the atomic erbium-dysprosium (Er-168-Dy-164) and dysprosium-dysprosium (Dy-164-Dy-162) mixtures. The miscibility is quantified by the overlap of the two-component densities, using an appropriate defined parameter. By verifying that stable regimes for pure-dipolar coupled BECs are only possible in pancake-type traps, we obtain some non-trivial local minimum biconcave-shaped states with density oscillations in both components. For non-dipolar systems with repulsive interactions, we show that immiscible stable configurations are also possible in cigar-type geometries. The main role of the trap aspect ratio and inter-species contact interaction for the miscibility is verified for different configurations, from non-dipolar to pure dipolar systems.