  Density functional theory with local spin density approximation has been used
to propose possible room temperature ferromagnetism in N-doped NaCl-type BaO.
Pristine BaO is a wide bandgap semiconductor, however, N induces a large
density of states at the Fermi level in the nonmagnetic state, which suggests
magnetic instability within the Stoner mean field model. The spin-polarized
calculations show that N-doped BaO is a true half- metal, where N has a large
magnetic moment, which is mainly localized around the N atoms and a small
polarization at the O sites is also observed. The origin of magnetism is linked
to the electronic structure. The ferromagnetic(FM) and antiferromagnetic (AFM)
coupling between the N atoms in BaO reveal that doping N atoms have a FM ground
state, and the calculated transition temperature ($T_{C}$), within the
Heisenberg mean field theory, theorizes possible room temperature FM in N-doped
BaO. Nitrogen also induces ferromagnetism when doping occurs at surface O site
and has a smaller defect formation energy than the bulk N-doped BaO. The
magnetism of N-doped BaO is also compared with Co-doped BaO, and we believe
that N has a greater potential for tuning magnetism in BaO than Co.
