Chiral Majorana hinge modes in superconducting Dirac materials

Chiral Majorana hinge modes are characteristic of a second-order topological superconductor in three dimensions. Here we systematically study pairing symmetry the point group D_{2h}, and find that leading channels can be s-, d-, s+id-wave Dirac materials. Except for odd-parity s-wave superconductivity, is topologically nontrivial possesses surface modes. The chiral characterized by winding number quadrupole moment, or quantized quadruple moment at symmetrically invariant point. Our findings suggest strong spin-orbital coupling, crystalline symmetries electron-electron interaction materials may provide microscopic mechanism to realize without utilizing proximity effect external fields.