  As a half-metal is spin-polarized at its Fermi level by definition, it was
conventionally thought to have little proximity effect to an s-wave
superconductor. Here we show that, with interface spin-orbit coupling, $p_x
+ip_y$ superconductivity without spin degeneracy is induced on the half-metal,
and we give an estimate of its bulk energy gap. Therefore a single-band
half-metal can give us a topological superconductor with a single chiral
Majorana edge state. Our band calculation shows that two atomic layers of VTe
or CrO$_2$ is a single-band half-metal for a wide range ($\sim$0.1eV) of Fermi
energy and thus is a suitable candidate material.
