Dirac monopoles with polar-core vortex induced by spin-orbit coupling in spinor Bose-Einstein condensates

TL;DR

This paper demonstrates the creation and stability of Dirac monopoles with polar-core vortices in spinor Bose-Einstein condensates influenced by spin-orbit coupling, revealing phase transitions and new detection methods.

Contribution

It introduces a novel method to generate stable Dirac monopoles with polar-core vortices using spin-orbit coupling in Bose-Einstein condensates, and explores their phase transitions and transformations.

Findings

Monopoles are stable and detectable via vortex line imaging.

Increasing spin-orbit coupling transforms monopoles into square lattice structures.

Interaction strength induces phase transitions from polar-core to Mermin-Ho vortices.

Abstract

We report Dirac monopoles with polar-core vortex induced by spin-orbit coupling in ferromagnetic Bose-Einstein condensates, which are attached to two nodal vortex lines along the vertical axis. These monopoles are more stable in the time scale of experiment and can be detected through directly imaging vortex lines. When the strength of spin-orbit coupling increases, Dirac monopoles with vortex can be transformed into those with square lattice. In the presence of spin-orbit coupling, increasing the strength of interaction can induce a cyclic phase transition from Dirac monopoles with polar-core vortex to those with Mermin-Ho vortex. The spin-orbit coupled Bose-Einstein condensates not only provide a new unique platform for investigating exotic monopoles and relevant phase transitions, but also can preserve stable monopoles after a quadrupole field is turned off.