Tetragonal CuO: A new end member of the 3d transition metal monoxides

TL;DR

This paper reports the synthesis of a tetragonal form of CuO using epitaxial thin film deposition, revealing enhanced ionic bonding and suggesting high-temperature antiferromagnetic properties as an end member of 3d transition metal monoxides.

Contribution

It introduces a new tetragonal phase of CuO synthesized via epitaxial growth, expanding the understanding of 3d transition metal monoxides.

Findings

Tetragonal CuO has an increased charge transfer gap.

Bonding in tetragonal CuO is more ionic.

Predicted high T_N antiferromagnetic behavior.

Abstract

Monoclinic CuO is anomalous both structurally as well as electronically in the 3$d$ transition metal oxide series. All the others have the cubic rock salt structure. Here we report the synthesis and electronic property determination of a tetragonal (elongated rock salt) form of CuO created using an epitaxial thin film deposition approach. In situ photoelectron spectroscopy suggests an enhanced charge transfer gap $\Delta$ with the overall bonding more ionic. As an end member of the 3d transition monoxides, its magnetic properties should be that of a high $T_N$ antiferromagnet.