Topological superconductivity and Majorana fermions in half-metal / superconductor heterostructure

A half-metal is by definition spin-polarized at its Fermi level and therefore was conventionally thought to have little proximity effect to an $s$-wave superconductor. Here we show that if there is spin-orbit coupling at the interface between a single-band half-metal and an $s$-wave superconductor, $p_x + ip_y$ superconductivity would be induced on the half-metal. This can give us topological superconductor with a single chiral Majorana edge state. We show that two atomic layers of CrO$_2$ or CrTe gives us the single-band half-metal and is thus a candidate material for realizing this physics.