Magnetic phase transitions of spin-1 ultracold bosons in a cubic optical lattice

TL;DR

This paper explores the phase transitions of spin-1 ultracold bosons in a cubic optical lattice, revealing complex phase diagrams, a spin-singlet condensate, and temperature-induced phase changes, with implications for experimental observation.

Contribution

It provides the first detailed phase diagram of spin-1 bosons in a lattice, including the spin-singlet condensate and temperature-driven phase transitions, using bosonic dynamical mean-field theory.

Findings

Existence of a spin-singlet condensate phase.

Finite temperature induces superfluid to Mott insulator transitions.

Critical temperatures for phases are estimated for experiments.

Abstract

We investigate strongly correlated spin-1 ultracold bosons with antiferromagnetic interactions in a cubic optical lattice, based on bosonic dynamical mean-field theory. Rich phase diagrams of the system are mapped out at both zero and finite temperature, and in particular the existence of a spin-singlet condensate is established. Interestingly, at finite temperature, we find that the superfluid can be heated into a Mott insulator with even (odd) filling via a first- (second-) order phase transition, analogous to the Pomeranchuk effect in $^{3}$He. Moreover, for typical experimental setups, we estimate the critical temperatures for different ordered phases and our results suggest that direct experimental observation of these phases is promising.