Metallic interface at the boundary between band and Mott insulators

TL;DR

This study models the electronic properties of LaTiO3/SrTiO3 heterostructures, revealing a metallic interface state influenced by Coulomb interactions and dielectric properties, consistent with experimental observations.

Contribution

It introduces a quasi one-dimensional lattice model with Coulomb interactions to analyze metallic interface states in Mott/band insulator heterostructures, complementing infinite-dimensional results.

Findings

Metallic state at the interface depends on dielectric constant.

Antiferromagnetic correlations persist into the metallic region.

Results agree with previous infinite-dimensional models.

Abstract

Motivated by experiments on atomically smooth layers of LaTiO$_3$, a Mott insulator, sandwiched between layers of SrTiO$_3$, a band insulator, a simple model for such heterostructures is studied using quasi one-dimensional lattices and the Lanczos method. Taking both the local and long-range Coulomb interactions into account, and computing the layer dependent local density of states, a metallic state was found at the interface whose extent strongly depends on the dielectric constant of the material. We also observed that the antiferromagnetic correlations in the bulk Mott phase persist into the metallic region. Our conclusions are in excellent agreement with recently reported results for this model in the opposite limit of infinite dimensions, thus providing an alternative tool to study electronic reconstruction effects in heterostructures.