Electronic phase transitions in the half-filled ionic Hubbard model

TL;DR

This paper investigates electronic phase transitions in the half-filled ionic Hubbard model using dynamical mean field theory, revealing a sequence of phases and a novel coexistence region.

Contribution

It provides a detailed dynamical mean field analysis of phase transitions in the ionic Hubbard model, highlighting a new coexistence phase.

Findings

Sequence of phase transitions from band insulator to metal to Mott insulator

Existence of a critical region where metallic phase vanishes

Identification of a coexistence phase between band and Mott insulators

Abstract

A detailed study of electronic phase transitions in the ionic Hubbard model at half filling is presented. Within the dynamical mean field approximation a series of transitions from the band insulator via a metallic state to a Mott-Hubbard insulating phase is found at intermediate values of the one-body potential $\Delta$ with increasing the Coulomb interaction $U$. We obtain a critical region in which the metallic phase disappears and a {\it novel} coexistence phase between the band and the Mott insulating state sets in. Our results are consistent with those obtained at low dimensions, thus they provide a concrete description for the charge degrees of freedom of the ionic Hubbard model.