  Based on the different covalent versus ionic chemical bonding and
isoelectronic rutile CrO2, CrNF is proposed starting from ordered rutile
derivative structures subjected to full geometry optimizations. The ground
state structure defined from cohesive energies is of MgUO4-type, characterized
by short covalent Cr-N and long ionic Cr-F distances. Like CrO2 it is a
half-metallic ferromagnet with M = 2 Bohr Magnetons integer magnetization per
formula unit with reduced band gap at minority spins. Major differences of
magnetic response to pressure characterize CrNF as a soft ferromagnet versus
hard magnetic CrO2. The chemical bonding properties point to prevailing
covalent Cr-N versus ionic Cr-F bonding. Synthesis routes with two different
protocols are proposed and analyzed.
