Peter Grünberg Institut and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
Institute for Advanced Simulation, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
Nat Commun. 2017 Apr 21;8:14976. doi: 10.1038/ncomms14976.
New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies. Here we demonstrate that stoichiometric BiTe, which is a natural superlattice of alternating two BiTe quintuple layers and one Bi bilayer, is a dual 3D topological insulator where a weak topological insulator phase and topological crystalline insulator phase appear simultaneously. By density functional theory, we find indices (0;001) and a non-zero mirror Chern number. We have synthesized BiTe by molecular beam epitaxy and found evidence for its topological crystalline and weak topological character by spin- and angle-resolved photoemission spectroscopy. The dual topology opens the possibility to gap the differently protected metallic surface states on different surfaces independently by breaking the respective symmetries, for example, by magnetic field on one surface and by strain on another surface.
新的三维（3D）拓扑相可以在包含已知二维拓扑成分的超晶格中出现。在这里，我们证明了化学计量比的 BiTe 是一个由交替的两个 BiTe 五重层和一个 Bi 双层组成的自然超晶格，它是一个双 3D 拓扑绝缘体，其中同时出现了弱拓扑绝缘体相和拓扑晶体绝缘体相。通过密度泛函理论，我们发现了指标（0；001）和非零的镜像陈数。我们通过分子束外延法合成了 BiTe，并通过自旋和角度分辨光发射谱找到了其拓扑晶体和弱拓扑性质的证据。这种双重拓扑结构为通过打破各自的对称性（例如，在一个表面上施加磁场，在另一个表面上施加应变）独立地在不同表面上产生受保护的金属表面态的能隙提供了可能性。
