Hybrid density-functional calculation of the electronic and magnetic structures of tetragonal CuO

The electronic and magnetic properties of recently synthesized tetragonal CuO with $c/a>1$ is calculated by means of hybrid density-functional theory. We predict that this tetragonal phase orders antiferromagnetically and has an exceptionally high Ne\'el temperature TN≈800 K, which makes it an ideal candidate for doping experiments and a potential parent of superconductors. The electronic structure is characterized by a charge-transfer gap of 2.7 eV whereas the magnetic properties are dominated by the antiferromagnetic Cu-O-Cu interactions along the nearest-neighbor [100] direction. In addition, we predict the second tetragonal CuO phase with a $c/a$ ratio $<1$ with a different antiferromagnetic ordering and a similar high TN. We suggest that this phase could be synthesized by epitaxial growth.