Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides
Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides
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DOI：
10.1038/nmat5031
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发表时间：
2018-01-01
期刊：
影响因子：
41.2
通讯作者：
King, P. D. C.
中科院分区：
文献类型：
--
作者：
Bahramy, M. S.;Clark, O. J.;King, P. D. C.
过渡金属二硫属化物（TMD）以其丰富多样的体相性质而闻名，而它们的单层变体已成为石墨烯之外二维材料中最突出的例子之一。它们不同的基态在很大程度上取决于过渡金属d-电子衍生的电子态，迄今为止，绝大多数注意力都集中在这一点上。在这里，我们专注于硫族衍生状态。从密度泛函理论计算与自旋和角度分辨的光电发射，我们发现，这些一般主机共存的I型和II型三维体狄拉克费米子以及梯子的拓扑表面状态和表面共振。我们展示了这些自然出现在一个单一的p-轨道流形作为一个三角晶场的一般后果，因此可以预期在大量的化合物。我们已经在六个不同的TMD中证明了它们的存在，开辟了调整并最终利用它们的拓扑物理学的途径。
Transition-metal dichalcogenides (TMDs) are renowned for their rich and varied bulk properties, while their single-layer variants have become one of the most prominent examples of two-dimensional materials beyond graphene. Their disparate ground states largely depend on transition metal d-electron-derived electronic states, on which the vast majority of attention has been concentrated to date. Here, we focus on the chalcogen-derived states. From density-functional theory calculations together with spin-and angle-resolved photoemission, we find that these generically host a co-existence of type-I and type-II three-dimensional bulk Dirac fermions as well as ladders of topological surface states and surface resonances. We demonstrate how these naturally arise within a single p-orbital manifold as a general consequence of a trigonal crystal field, and as such can be expected across a large number of compounds. Already, we demonstrate their existence in six separate TMDs, opening routes to tune, and ultimately exploit, their topological physics.