  We employ density functional theory using the modified Becke-Johnson (mBJ)
approach to investigate the electronic and magneto-optical properties of
N-doped NaTaO$_3$. The mBJ results reveal a half metallic nature of NaTaO$_2$N,
in contrast to results obtained by the generalized gradient approximation. We
find a giant polar Kerr rotation of 2.16$^{\circ}$ at 725 nm wave length
(visible region), which is high as compared to other half metallic perovskites
as well as to the prototypical half metal PtMnSb.
