Phase diagrams of the Bose-Hubbard model at finite temperature

TL;DR

This paper analyzes the finite-temperature phase diagrams of the Bose-Hubbard model, focusing on superfluid and Mott insulator phases, using Green's functions and Hubbard operators, and examining thermal effects on phase transitions.

Contribution

It provides a detailed analysis of the finite-temperature phase diagrams of the Bose-Hubbard model, including the effects of thermal activation on phase boundaries and Mott lobes.

Findings

Identification of superfluid and Mott insulator regions in phase diagrams.

Construction of phase diagrams in the (μ,t) and (T,μ) planes.

Analysis of thermal activation effects on Mott lobes.

Abstract

The phase transitions in the Bose-Hubbard model are investigated. A single-particle Green's function is calculated in the random phase approximation and the formalism of the Hubbard operators is used. The regions of existence of the superfluid and Mott insulator phases are established and the $(\mu,t)$ (the chemical potential -- transfer parameter) phase diagrams are built. The influence of temperature change on this transition is analyzed and the phase diagram in the $(T,\mu)$ plane is constructed. The role of thermal activation of the ion hopping is investigated by taking into account the temperature dependence of the transfer parameter. The reconstruction of the Mott-insulator lobes due to this effect is analyzed.