Oxide superlattices with alternating p and n interfaces

TL;DR

This paper investigates oxide superlattices composed of LaAlO3 and SrTiO3 with alternating p and n interfaces, revealing their dielectric properties, insulator-metal transition, and potential for exciton condensation through first-principles calculations.

Contribution

It provides a first-principles analysis and a simple model to understand the dielectric behavior and insulator-metal transition in oxide superlattices with p and n interfaces.

Findings

Charge at interfaces matches ionic charge predictions.

Layer thickness influences spontaneous polarization and electron gas manipulation.

Large piezoresistance effects observed near insulator-metal transition.

Abstract

The physics of oxide superlattices is considered for pristine (001) multilayers of the band insulators LaAlO3 and SrTiO3 with alternating p and n interfaces. First principles results and a model of capacitor plates offer a simple paradigm to understand their dielectric properties and the insulator to metal transition (IMT) at interfaces with increasing layer thickness. The charge at insulating interfaces is found to be as predicted from the formal ionic charges, not populations. Different relative layer thicknesses produce a spontaneous polarization of the system, and allow manipulation of the interfacial electron gas. Large piezoresistance effects can be obtained from the sensitivity of the IMT to lateral strain. Carrier densities are found to be ideal for exciton condensation.