Motion of vortices in ferromagnetic spin-1 BEC

TL;DR

This paper explores the dynamics of nonsingular vortices in ferromagnetic spin-1 Bose-Einstein condensates, revealing how skyrmion cores and uniaxial anisotropy influence vortex motion and associated forces.

Contribution

It introduces a hydrodynamic analysis of vortex motion in spin-1 BECs, highlighting the role of skyrmion charge and anisotropy, and compares results with magnetic vortex theories.

Findings

Skyrmion cores have charge tunable by anisotropy.

Mass and spin currents circulate around vortices.

Transverse gyrotropic force is proportional to skyrmion charge.

Abstract

The paper investigates dynamics of nonsingular vortices in a ferromagnetic spin-1 BEC, where spin and mass superfluidity coexist in the presence of uniaxial anisotropy (linear and quadratic Zeeman effect). The analysis is based on hydrodynamics following from the Gross-Pitaevskii theory. Cores of nonsingular vortices are skyrmions with charge, which is tuned by uniaxial anisotropy and can have any fractal value between 0 and 1. There are circulations of mass and spin currents around these vortices. The results are compared with the equation of vortex motion derived earlier in the Landau-Lifshitz-Gilbert theory for magnetic vortices in easy-plane ferromagnetic insulators. In the both cases the transverse gyrotropic force (analog of the Magnus force in superfluid and classical hydrodynamics) is proportional to the charge of skyrmions in vortex cores.