High Tc superconductivity in superlattices of insulating oxides

TL;DR

This paper demonstrates high-temperature superconductivity up to 40 K in superlattices of insulating oxides CaCuO2 and SrTiO3, achieved through interface engineering and oxygen doping.

Contribution

It reports the discovery of superconductivity in oxide superlattices with interface-induced doping, a novel approach in high Tc superconductor research.

Findings

Superconductivity observed at interfaces with Tc up to 40 K.

Superconductivity depends on high oxygen atmosphere during growth.

Charge transfer at interfaces induces hole doping in CuO2 planes.

Abstract

We report the occurrence of superconductivity, with maximum Tc = 40 K, in superlattices (SLs) based on two insulating oxides, namely CaCuO2 and SrTiO3. In these (CaCuO2)n/(SrTiO3)m SLs, the CuO2 planes belong only to CaCuO2 block, which is an antiferromagnetic insulator. Superconductivity, confined within few unit cells at the CaCuO2/SrTiO3 interface, shows up only when the SLs are grown in a highly oxidizing atmosphere, because of extra oxygen ions entering at the interfaces. Evidence is reported that the hole doping of the CuO2 planes is obtained by charge transfer from the interface layers, which act as charge reservoir.