Vortex lattices in binary Bose-Einstein condensates with dipole-dipole interactions

TL;DR

This paper investigates the structure and stability of vortex lattices in two-component dipolar Bose-Einstein condensates, exploring how interactions and miscibility influence lattice configurations through theoretical modeling and phase diagrams.

Contribution

It provides the first detailed analysis of vortex lattice structures in dipolar BEC mixtures with varying miscibility, using effective 2D coupled Gross-Pitaevskii equations and phase diagrams.

Findings

Diverse vortex lattice shapes in highly miscible mixtures.

Circular and square lattice patterns in less miscible mixtures.

Phase diagrams mapping lattice types to interaction parameters.

Abstract

We study the structure and stability of vortex lattices in two-component rotating Bose-Einstein condensates with intrinsic dipole-dipole interactions (DDIs) and contact interactions. To address experimentally accessible coupled systems, we consider $^{164}$Dy-$^{162}$Dy and $^{168}$Er-$^{164}$Dy mixtures, which feature different miscibilities. The corresponding dipole moments are $\mu_{\mathrm{Dy}}=10\mu_{\mathrm{B}}$ and $\mu_{\mathrm{Er}}= 7\mu_{\mathrm{B}}$, where $\mu_{\mathrm{B}}$ is the Bohr magneton. For comparison, we also discuss a case where one of the species is non dipolar. Under a large aspect ratio of the trap, we consider mixtures in the pancake-shaped format, which are modeled by effective two-dimensional coupled Gross-Pitaevskii equations, with a fixed polarization of the magnetic dipoles. Then, the miscibility and vortex-lattice structures are studied, by varying the coefficients of the contact interactions (assuming the use of the Feshbach-resonance mechanism) and the rotation frequency. We present phase diagrams for several types of lattices in the parameter plane of the rotation frequency and ratio of inter- and intra-species scattering lengths. The vortex structures are found to be diverse for the more miscible $^{164}$Dy-$^{162}$Dy mixture, with a variety of shapes, whereas, for the less miscible case of $^{168}$Er-$^{164}$Dy, the lattice patterns mainly feature circular or square formats.