  Based on first-principles calculations, we propose a sandwich structure
composed of a G-type anti-ferromagnetic (AFM) Mott insulator LaCrO$_3$ grown
along the [001] direction with one atomic layer replaced by an
inverse-perovskite material Sr$_3$PbO. We show that the system is in a
topologically nontrivial phase characterized by simultaneous nonzero charge and
spin Chern numbers, which can support a spin-polarized and dissipationless edge
current in a finite system. Since these two materials are stable in bulk and
match each other with only small lattice distortions, the composite material is
expected easy to synthesize.
