Edge states and local electronic structure around an adsorbed impurity in a topological superconductor

Recently, topological superconducting states have attracted much interest. In this paper, we consider a topological superconductor with Z2 topological mirror order [Y.-Y. Tai, Phys. Rev. B 91, 041111(R) (2015)PRBMDO1098-012110.1103/PhysRevB.91.041111] and s±-wave superconducting pairing symmetry, within a two-orbital model originally designed for iron-based superconductivity [Y.-Y. Tai, Europhys. Lett. 103, 67001 (2013)EULEEJ0295-507510.1209/0295-5075/103/67001]. We predict the existence of gapless edge states. We also study the local electronic structure around an adsorbed interstitial magnetic impurity in the system, and find the existence of low-energy in-gap bound states even with a weak spin polarization on the impurity. We also discuss the relevance of our results to a recent scanning tunneling microscopy experiment on a Fe(Te,Se) compound with an adsorbed Fe impurity [J.-X. Yin, Nat. Phys. 11, 543 (2015)10.1038/nphys3371], for which our density functional calculations show the Fe impurity is spin polarized.