Insulator-Superfluid transition of spin-1 bosons in an optical lattice in magnetic field

TL;DR

This paper investigates the phase transition of spin-1 bosons in an optical lattice under a magnetic field, revealing multiple superfluid phases depending on particle number, which differs from the field-free case.

Contribution

It introduces a mean-field phase diagram for spin-1 bosons in a magnetic field, showing multiple superfluid phases based on particle number and magnetic interactions.

Findings

Transition can lead to different superfluid phases with spins aligned or opposite to the field

The phase diagram depends on particle number and magnetic interactions

Distinct from the field-free case where a single polar superfluid state occurs

Abstract

We study the insulator-superfluid transition of spin-1 bosons in an optical lattice in a uniform magnetic field. Based on a mean-field approximation we obtained a zero-temperature phase diagram. We found that depending on the particle number the transition for bosons with antiferromagnetic interaction may occur into different superfluid phases with spins aligned along or opposite to the field direction. This is qualitatively different from the field-free transition for which the mean-field theory predicts a unique (polar) superfluid state for any particle number.