  We present a unified band structure model to explain magnetic ordering in
Mn-doped semiconductors. This model is based on the $p$-$d$ and $d$-$d$ level
repulsions between the Mn ions and host elements and can successfully explain
magnetic ordering observed in all Mn doped II-VI and III-V semiconductors such
as CdTe, GaAs, ZnO, and GaN. This model, therefore, provides a simple guideline
for future band structure engineering of magnetic semiconductors.
