  We report on a theoretical and experimental study of CuMn-V antiferromagnets.
Previous works showed low-temperature antiferomagnetism and semimetal
electronic structure of the semi-Heusler CuMnSb. In this paper we present
theoretical predictions of high-temperature antiferromagnetism in the stable
orthorhombic phases of CuMnAs and CuMnP. The electronic structure of CuMnAs is
at the transition from a semimetal to a semiconductor and we predict that CuMnP
is a semiconductor. We show that the transition to a semiconductor-like band
structure upon introducing the lighter group-V elements is present in both the
metastable semi-Heusler and the stable orthorhombic crystal structures. On the
other hand, the orthorhombic phase is crucial for the high N\'eel temperature.
Results of X-ray diffraction, magnetization, transport, and neutron diffraction
measurements we performed on chemically synthesized CuMnAs are consistent with
the theory predictions.
