Strongly renormalized quasi-two-dimensional electron gas in a heterostructure with correlation effects

TL;DR

This paper investigates strong electron correlation effects in a heterostructure, revealing the formation of a strongly renormalized quasi-two-dimensional electron gas near interfaces, influenced by correlation strength and heterostructure width.

Contribution

It introduces a model using Kotliar-Ruckenstein slave-boson theory to analyze correlation effects in heterostructures, highlighting the emergence of a confined, strongly renormalized electron gas.

Findings

Quasiparticles form a quasi-two-dimensional electron gas near interfaces.

Strong correlations lead to a narrow, confined electron region.

Nontrivial momentum dependence affects optical properties.

Abstract

We present aspects of strong electron correlation in a model of a BI/M/BI heterostructure where BI is a band insulator and M can be tuned from a metal to a Mott insulator by varying the on-site repulsion. An effective one-dimensional Schroedinger equation for the low-energy part is derived in the framework of the Kotliar-Ruckenstein slave-boson mean-field theory and solved self-consistently for a wide range of the on-site interaction strength and of the width of the sandwiched material M. In the strongly interacting limit coherent quasiparticles responsible for metallic behavior are confined to a relatively narrow region near the interfaces where they form a quasi-two-dimensional electron gas. Due to the lack of spatial homogeneity these quasiparticles intrinsically obtain a nontrivial dependence on the transverse momentum which for example enters the low-energy behavior of the optical conductivity.