Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides

Research output: Contribution to journalArticlepeer-review

  • External authors:
  • O. J. Clark
  • B. -J. Yang
  • J. Feng
  • L. Bawden
  • J. M. Riley
  • I. Markovic
  • F. Mazzola
  • V. Sunko
  • D. Biswas
  • S. P. Cooil
  • M. Jorge
  • J. W. Wells
  • M. Leandersson
  • T. Balasubramanian
  • J. Fujii
  • I. Vobornik
  • J. E. Rault
  • T. K. Kim
  • M. Hoesch
  • K. Okawa
  • M. Asakawa
  • T. Sasagawa
  • T. Eknapakul
  • W. Meevasana
  • P. D. C. King


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.

Bibliographical metadata

Original languageEnglish
JournalNature Materials
Publication statusPublished - 27 Nov 2018