Topological superconducting phase and Majorana fermions in half-metal/superconductor heterostructures

Abstract

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 ${p}_{x}+i{p}_{y}$ 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 ($\ensuremath{\sim}$0.1 eV) of Fermi energy and thus is a suitable candidate material.