Interface hole-doping in cuprate-titanate superlattices

TL;DR

This study uses LSDA+U calculations to show that interface polarity in cuprate-titanate superlattices causes hole doping in CuO$_2$ layers, influencing superconductivity in engineered devices.

Contribution

It reveals the mechanism of interface hole doping due to polarity effects in cuprate-titanate heterostructures, impacting superconducting properties.

Findings

Metallic state with hole carriers in CuO$_2$ and interface TiO$_2$, SrO planes.

Interface polarity causes effective doping of CuO$_2$ layers.

Pre-doping influences superconducting behavior in superlattice devices.

Abstract

The electronic structure of interfaces between YBa$_2$Cu$_3$O$_6$ and SrTiO$_3$ is studied using local spin density approximation (LSDA) with intra-atomic Coulomb repulsion (LSDA+U). We find a metallic state in cuprate/titanate heterostructures with the hole carriers concentrated substantially in the CuO$_2$-layers and in the first interface TiO$_2$ and SrO planes. This effective interface doping appears due to the polarity of interfaces, caused by the first incomplete copper oxide unit cell. Interface-induced high pre-doping of CuO$_2$-layers is a key mechanism controlling the superconducting properties in engineered field-effect devices realized on the basis of cuprate/titanate superlattices.