On the criteria for superconducting superlattices using CaCuO 2

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 BaBiO 3 , LaCrO 3 , EuFeO 3 , and Ca 2 Fe 2 O 5 as candidate materials. We use molecular beam epitaxy as a synthesis tool for the development of artificial superconducting superlattices in combination with infinte-layer CaCuO 2 . We find that (1) layer lattice matching, (2) thermodynamic compatibility and (3) absence of diffusion of any element other than Cu into CuO 2 planes are key criteria to realize superconductivity. For brown-millerite Ca 2 Fe 2 O 5 /CaCuO 2 superlattices, criteria 1–3 are met and superconductivity emerges.