Quasi-two-dimensional soliton in a self-repulsive spin-orbit-coupled dipolar binary condensate

TL;DR

This paper investigates the formation and types of solitons in a quasi-2D spin-orbit coupled Bose-Einstein condensate, revealing new soliton structures and the effects of dipolar interactions.

Contribution

It introduces the existence of square-lattice solitons in a quasi-2D SO-coupled BEC and analyzes the impact of dipolar interactions on soliton types.

Findings

Multi-ring solitons exist at weak SO coupling in nondipolar BECs.

Square-lattice solitons emerge at intermediate SO coupling.

Dipolar interactions restrict solitons to circularly-asymmetric and stripe types.

Abstract

We study the formation of solitons in a uniform quasi-two-dimensional (quasi-2D) spin-orbit (SO) coupled self-repulsive binary dipolar and nondipolar Bose-Einstein condensate (BEC) using the mean-field Gross-Pitaevskii equation. For a weak SO coupling, in a nondipolar BEC, one can have three types of degenerate solitons: a multi-ring soliton with intrinsic vorticity of angular momentum projection $+1$ or $-1$ in one component and 0 in the other, a circularly-asymmetric soliton and a stripe soliton with stripes in the density. For an intermediate SO couplings, the multi-ring soliton ceases to exist and there appears a square-lattice soliton with a spatially-periodic pattern in density on a square lattice, in addition to the degenerate circularly-asymmetric and stripe solitons. In the presence of a dipolar interaction, with the polarization direction aligned in the quasi-2D plane, only the degenerate circularly-asymmetric and stripe solitons appear.