Robustness against non-magnetic impurities in topological superconductors

Abstract

We study The robustness against non-magnetic impurities in a three-dimensional topological superconductor, focusing on an effective model (massive Dirac Bogoliubov-de Gennes (BdG) Hamiltonian with s-wave on-site pairing) of CuxBi2Se3 with The parameter set determined by The first-principles calculation. With The use of The self-consistent T- matrix approximation for impurity scattering, we discuss The impurity-concentration dependence of The zero-energy density of states. We show that a single material variable, measuring relativistic effects in The Dirac-BdG Hamiltonian, well characterizes The numerical results. In The nonrelativistic limit, The odd-parity fully-gapped topological superconductivity is fragile against non-magnetic impurities, since this superconductivity can be mapped onto The p-wave superconductivity. On The other hand, in The ultrarelativistic limit, The superconductivity is robust against The non-magnetic impurities, since The effective model has The s-wave superconductivity. We derive The effective Hamiltonian in The both limit.