Topological insulators in filled skutterudites

We propose new topological insulators in cerium-filled skutterudite (FS) compounds based on ab initio calculations. We find that two compounds, CeOs ₄As ₁₂ and CeOs ₄Sb ₁₂, are zero gap materials with band inversions between Os-d and Ce-f orbitals, similar to HgTe. Both compounds are predicted to become topological Kondo insulators at low temperatures, which are Kondo insulators in the bulk but with robust Dirac surface states on the boundary. Furthermore, this family of topological insulators has more unique features. Due to similar lattice parameters there will be a good proximity effect with other superconducting FS compounds, which may realize Majorana fermions. Additionally, the experimentally observed antiferromagnetic phase of CeOs ₄Sb ₁₂ at very low temperature provides a way to realize the massive Dirac fermion with topological magnetoelectric effects.