Successive phase transitions at finite temperatures of the supersolid in the three-dimensional extended Bose-Hubbard model

TL;DR

This study explores the finite temperature phase transitions of the three-dimensional extended Bose-Hubbard model, revealing successive superfluid and solid transitions, and analyzing the competition between these orders through simulations and mean-field theory.

Contribution

It provides the first detailed phase diagram of the supersolid state at finite temperatures in this model, combining quantum Monte Carlo simulations with mean-field analysis.

Findings

Identified successive superfluid and solid phase transitions.

Mapped the finite temperature phase diagram including supersolid.

Analyzed the competition between superfluid and solid orders.

Abstract

We study the finite temperature properties of the extended Bose-Hubbard model on a cubic lattice. This model exhibits the so-called supersolid state. To start with, we investigate ordering processes by quantum Monte Carlo simulations, and find successive superfluid and solid phase transitions. There, we find that the two order parameters compete with each other. We obtain the finite temperature phase diagram, which contains the superfluid, the solid, the supersolid and the disordered phase. We develop a mean-field theory to analyze the ordering processes and compare the result with that obtained by simulations, and discuss the mechanism of the competition of these two orders. We also study how the supersolid region shrinks as the on-site repulsion becomes strong.