Topological properties of multilayers and surface steps in the SnTe material class
Abstract
Surfaces of multilayer semiconductors typically have regions of atomically flat terraces separated by atomhigh steps. Here we investigate the properties of the lowenergy states appearing at the surface atomic steps in Sn_{1 x}Pb_{x}Te_{1 y}Se_{y} . We identify the important approximate symmetries and use them to construct relevant topological invariants. We calculate the dependence of mirror and spinresolved Chern numbers on the number of layers and show that the step states appear when these invariants are different on the two sides of the step. Moreover, we find that a particlehole symmetry can protect onedimensional Weyl points at the steps. Since the local density of states is large at the step the system is susceptible to different types of instabilities, and we consider an easyaxis magnetization as one realistic possibility. We show that magnetic domain walls support lowenergy bound states because the regions with opposite magnetization are topologically distinct in the presence of nonsymmorphic chiral and mirror symmetries, providing a possible explanation for the zerobias conductance peak observed in the recent experiment [Mazur et al., Phys. Rev. B 100, 041408(R) (2019), 10.1103/PhysRevB.100.041408].
 Publication:

Physical Review B
 Pub Date:
 September 2019
 DOI:
 10.1103/PhysRevB.100.121107
 arXiv:
 arXiv:1812.02168
 Bibcode:
 2019PhRvB.100l1107B
 Keywords:

 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 Phys. Rev. B 100, 121107 (2019)