On the criteria for superconducting superlattices using CaCuO2 *

Abstract

The manifestation of superconductivity in cuprate superconductors is concerted to copper-oxygen planes. To maintain charge neutrality, the copper-oxygen planes are embedded between materials, that are electronically insulating. Here, we introduce BaBiO3, LaCrO3, EuFeO3, and Ca2Fe2O5 as candidate materials. We use molecular beam epitaxy as a synthesis tool for the development of artificial superconducting superlattices in combination with infinte-layer CaCuO2. We find that (1) layer lattice matching, (2) thermodynamic compatibility and (3) absence of diffusion of any element other than Cu into CuO2 planes are key criteria to realize superconductivity. For brown-millerite Ca2Fe2O5/CaCuO2 superlattices, criteria 1–3 are met and superconductivity emerges.