Ferromagnetism in a two-component Bose-Hubbard model with a synthetic spin-orbit coupling

TL;DR

This paper investigates how synthetic spin-orbit coupling induces ferromagnetic long-range order in a one-dimensional two-component Bose-Hubbard model, revealing a novel phase transition detectable in current experiments.

Contribution

It demonstrates the emergence of ferromagnetic order due to spin-orbit coupling in a Bose-Hubbard model, a new phenomenon in this context.

Findings

Ferromagnetic order appears in both Mott insulator and superfluid phases.

Order results from spontaneous Z2 symmetry breaking.

Effect is observable with current synthetic spin-orbit coupling experiments.

Abstract

We study the effect of the synthetic spin-orbit coupling in a two-component Bose-Hubbard model in one dimension by employing the density-matrix renormalization group method. A ferromagnetic long-range order emerges in both Mott insulator and superfluid phases resulting from the spontaneous breaking of the $Z_2$ symmetry, when the spin-orbit coupling term becomes comparable to the hopping kinetic energy and the inter-component interaction is smaller than the intra-one as well. This novel effect is expected to be detectable with the present realization of the synthetic spin-orbit coupling in experiments.