Superconductivity in the Infinite Layer Compound CaCuO2

TL;DR

This paper discusses the emergence of superconductivity in CaCuO2, emphasizing the importance of pyramidal CuO2 coordination and its implications for doping and electronic structure.

Contribution

It introduces a new perspective on the CuO2 layer structure in CaCuO2, highlighting pyramidal coordination's role in superconductivity, based on spectroscopic and chemical analyses.

Findings

Superconductivity observed in CaCuO2 with specific doping.

Pyramidal CuO2 coordination is crucial for superconductivity.

Analysis supports the role of oxygens in the Cu2+ coordination.

Abstract

Superconductivity in the electric field-effect doped infinite layer compound CaCuO2 is considered. It is argued that in the superconducting CuO2 layer, next to the insulating Al2O3 overlayer, the coordination of the Cu2+ ions by oxygens is pyramidal rather than square planar. This view stems from existing NEXAFS and the analysis of HRETM results, as well as chemical considerations, and is discussed mainly for the hole doped but also the electron doped region of the phase diagramm.