2017/02/28 by M. S. Bahramy, O. J. Clark, Oliver J. Clark +39 · 4 citations
Chemistry · Materials Science · Physics and Astronomy · #2D Materials and Applications #Angle-resolved photoemission spectroscopy #Chemistry #Condensed matter physics #Density functional theory #Dirac (video compression format) #Dirac fermion #Electron #Electronic structure #Geometry #Graphene #Graphene research and applications #Manifold (fluid mechanics) #Physics #Quantum mechanics #Spin (aerodynamics) #Surface (topology) #Surface states #Topological Materials and Phenomena #Topology (electrical circuits) #Transition metal #cond-mat.mtrl-sci #cond-mat.supr-con
paper · pdf · doi:10.1038/nmat5031
published as Nature Materials 17, 21-28 (2018) (DOI 10.1038/nmat5031) · 10 pages, 4 figures
openalex publication_date 2017/11/27 · arxiv created 2018/07/19 · arxiv updated 2018/07/20 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
Transition-metal dichalcogenides (TMDs) are renowned for their rich and varied properties. They range from metals and superconductors to strongly spin-orbit-coupled semiconductors and charge-density-wave systems, with their single-layer variants one of the most prominent current examples of two-dimensional materials beyond graphene. Their varied ground states largely depend on the 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 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.