  Motivated by the ongoing interest in nitrides as materials for spintronics
applications we have studied effects of doping with magnetic transition-metal
elements (T=Cr,Mn,Fe,Co and Ni) on the electronic properties of semiconducting
scandium nitride. Using density functional together with the generalized
gradient approximation (GGA) as well as PBE0r hybrid functional (with different
mixing of the exact exchange), two different doping amounts 25\% ($\rm
Sc_{0.75}T_{0.25}N$) and 10\% ($\rm Sc_{0.9}T_{0.1}N$) have been investigated.
This is done in comparison to the reference compound ScN with a strong focus on
identifying candidates for half-metallic or semiconducting ferromagnetic ground
states. Within GGA, only $\rm Sc_{0.75}Cr_{0.25}N$ and $\rm
Sc_{0.75}Mn_{0.25}N$ are found to be semiconducting and half-metallic,
respectively. The use of hybrid functional changes drastically these finding,
where $\rm Sc_{0.75}Fe(Co,Ni)_{0.25}N$ become half-metals and $\rm
Sc_{0.75}Cr(Mn)_{0.25}N$ are found both semiconductors. However, additional
calculations assuming antiferromagnetic ordering revealed that $\rm
Sc_{0.75}Cr_{0.25}N$ is the only compound of this series, which prefers an
antiferromagnetic (and semiconducting) ground state. For the lower
concentration, $\rm Sc_{0.9}T_{0.1}N$, similar results have been predicted, and
all the doped nitrides are found to prefer ferromagnetic ground state over an
antiferromagnetic one.
