Abstract
The electronic and magnetic properties of newly 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 new cuprates. 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-neighbour [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 new phase could
be synthesized by epitaxial growth.