Surface and vortex states in topological nodal superconductors

Po-Yao Chang,
Dept Physics, University of Illinois, Urbana Champaign

We study gapless topological phases described by Bloch and  Bogoliubov-de Gennes Hamiltonians. A generalized bulk-boundary correspondence is discussed by relating the topological   properties in the bulk of gapless topological phases and the protected zero-energy states at the boundary. We explicitly compute the surface density of states of nodal noncentrosymmetric  superconductors (NCSs) and interpret the surface measurements in  experiments. In addition, we investigate Majorana vortex- bound states in both nodal and fully gapped NCSs using numerical as well as analytical methods. It is shown that different  nontrivial topological properties of the bulk Bogoliubov- quasiparticle wave functions reflect themselves in different  types of zero- energy vortex-bound states. In particular, it is found that in the case of the NCSs with tetragonal point-group symmetry, the stability of these Majorana zero modes is guaranteed by a combination of reflection, time-reversal, and particle-hole symmetry.