Persistence of symmetryprotected Dirac points at the surface of the topological crystalline insulator SnTe upon impurity doping
Abstract
We investigate the effect of a nonmagnetic donor impurity located at the surface of the SnTe topological crystalline insulator. In particular, the changes on the surface states due to a Sb impurity atom are analyzed by means of ab initio simulations of pristine and impuritydoped SnTe. Both semiinfinite and slab geometries are considered within the firstprinciples approach. Furthermore, minimal and Green's function continuum models are proposed with the same goal. We find that the Dirac cones are shifted down in energy upon doping; this shift strongly depends on the position of the impurity with respect to the surface. In addition, we observe that the width of the impurity band presents an evenodd behavior by varying the position of the impurity. This behavior is related to the position of the nodes of the wave function with respect to the surface, and hence it is a manifestation of confinement effects. We compare slab and semiinfinite geometries within the ab initio approach, demonstrating that the surface states remain gapless and their spin textures are unaltered in the doped semiinfinite system. In the slab geometry, a gap opens due to hybridization of the states localized at opposite surfaces. Finally, by means of a continuum model, we extrapolate our results to arbitrary positions of the impurity, clearly showing a nonmonotonic behavior of the Dirac cone.
 Publication:

arXiv eprints
 Pub Date:
 August 2021
 arXiv:
 arXiv:2108.06619
 Bibcode:
 2021arXiv210806619A
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 Paper published as Open Access