Persistence of symmetry-protected Dirac points at the surface of the topological crystalline insulator SnTe upon impurity doping

Abstract

Topologically protected surface states in semi-infinite SnTe are robust against Sb doping and preserve their spin texture, whereas in slabs they show a gap. These states are studied using first-principles and continuum model calculations.

Density Functional Theory Study of the Spin–Orbit Insulating Phase in SnTe Cubic Nanowires: Implications for Topological Electronics

“…The TCI phase is different from the conventional topological insulating phase; indeed, the linearly dispersing Dirac states on the high-symmetry surfaces of the TCIs are protected by crystal symmetries and not by time-reversal symmetry. SnTe and its substitutional alloys are TCIs with mirror symmetry, and the presence of the surface states is indicated by a nonzero integer topological invariant named the mirror Chern number. ,− Furthermore, it has been shown that SnTe is a helical, higher-order topological insulator. − It has been observed that the characteristic properties change by changing the size or dimensions (2D or 3D phase) of materials; namely, the properties will change if we move from bulk − to thin films. − For instance, SnTe is a trivial insulator at low thickness but becomes topological above some critical thickness , and is quite robust against impurity doping . Recently, the twinning in thin films as a function of the mirror Chern number was studied .…”

“… 32 − 34 For instance, SnTe is a trivial insulator at low thickness but becomes topological above some critical thickness 35 , 36 and is quite robust against impurity doping. 37 Recently, the twinning in thin films as a function of the mirror Chern number was studied. 38 By using scanning tunneling microscopy for Pb 1– x Sn x Se, we showed that atomically flat terraces in the Se sublattice separated by step edges of various heights are present.…”