Institut de Matériaux, Microélectronique et Nanosciences de Provence, Faculté St. Jérôme, Université Aix-Marseille, Marseille, France.
Phys Rev Lett. 2011 Jun 10;106(23):236806. doi: 10.1103/PhysRevLett.106.236806. Epub 2011 Jun 8.
We establish the presence of topologically protected edge states on the (001) surface of HgS in the zinc-blende structure using density-functional electronic structure calculations. The Dirac point of the edge state cone is very close to the bulk valence band maximum. The Dirac cone is extremely anisotropic with a very large electron velocity along one diagonal of the surface elementary cell x' and a nearly flat dispersion in the perpendicular direction y'. The strong anisotropy originates from a broken fourfold rotoinversion symmetry at the surface.
我们使用基于密度泛函理论的电子结构计算方法，在闪锌矿结构的 HgS（001）表面上确定了拓扑保护的边缘态的存在。边缘态锥的狄拉克点非常接近体价带顶。狄拉克锥具有极强的各向异性，在表面元胞的一个对角线上具有非常大的电子速度 x'，而在垂直方向 y'上的色散几乎是平的。这种强烈的各向异性源于表面处的四度旋转反演对称性破缺。
