CNRS, Aix-Marseille Université, IM2NP-UMR 7334, 13397 Marseille Cedex 20, France and Centre de Cadarache, Institut de Radioprotection et de Sûreté Nucléaire, PSN-RES/SAG/LETR, 13115 Saint Paul les Durance Cedex, France.
Phys Rev Lett. 2013 Oct 4;111(14):146803. doi: 10.1103/PhysRevLett.111.146803. Epub 2013 Oct 2.
Using density functional electronic structure calculations, we establish the consequences of surface termination and modification on protected surface states of metacinnabar (β-HgS). Whereas we find that the Dirac cone is isotropic and well separated from the valence band for the (110) surface, it is highly anisotropic at the pure (001) surface. We demonstrate that the anisotropy is modified by surface passivation because the topological surface states include contributions from dangling bonds. Such dangling bonds exist on all pure surfaces within the whole class HgX with X=S, Se, or Te and directly affect the properties of the Dirac cone. Surface modifications also alter the spatial location (depth and decay length) of the topologically protected edge states, which renders them essential for the interpretation of photoemission data.
利用密度泛函电子结构计算，我们确定了表面终止和修饰对辰砂（β-HgS）保护表面态的影响。我们发现，（110）表面的狄拉克锥是各向同性的，与价带很好地分离，但在纯净（001）表面，它具有强烈的各向异性。我们证明，由于拓扑表面态包括悬空键的贡献，表面钝化会改变各向异性。所有属于 HgX（X=S、Se 或 Te）的纯表面都存在这种悬空键，并且直接影响狄拉克锥的性质。表面修饰还改变了拓扑保护边缘态的空间位置（深度和衰减长度），这对解释光电子数据至关重要。
