The Bose-Hubbard model on a triangular lattice with diamond ring-exchange

TL;DR

This study investigates how ring-exchange interactions influence the phase diagram of bosons on a triangular lattice, revealing the suppression of the supersolid phase and the absence of a Bose-liquid phase.

Contribution

It provides the first detailed phase diagram of the Bose-Hubbard model with ring-exchange on a triangular lattice using the SGF algorithm.

Findings

Supersolid phase is rapidly destroyed by ring-exchange interactions.

No evidence of a Bose-liquid phase in the studied parameter range.

Ground-state phase diagram characterized by the absence of the Bose-liquid phase.

Abstract

Ring-exchange interactions have been proposed as a possible mechanism for a Bose-liquid phase at zero temperature, a phase that is compressible with no superfluidity. Using the Stochastic Green Function algorithm (SGF), we study the effect of these interactions for bosons on a two-dimensional triangular lattice. We show that the supersolid phase, that is known to exist in the ground state for a wide range of densities, is rapidly destroyed as the ring-exchange interactions are turned on. We establish the ground-state phase diagram of the system, which is characterized by the absence of the expected Bose-liquid phase.