Topological origin of the type-II Dirac fermions in PtSe2

Yiwei Li, Yunyouyou Xia, Sandy Adhitia Ekahana, Nitesh Kumar, Juan Jiang, Lexian Yang, Cheng Chen, Chaoxing Liu, Binghai Yan, Claudia Felser, Gang Li, Zhongkai Liu, Yulin Chen

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48 Scopus citations


Group VIII transition-metal dichalcogenides have recently been proposed to host type-II Dirac fermions. They are Lorentz-violating quasiparticles marked by a strongly tilted conic dispersion along a certain momentum direction and therefore have no analogs in the standard model. Using high-resolution angle-resolved photoemission spectroscopy, we systematically studied the electronic structure of PtSe2 in the full three-dimensional Brillouin zone. As predicted, a pair of type-II Dirac crossings is experimentally confirmed along the kz axis. Interestingly, we observed conic surface states around time-reversal-invariant momenta Γ and M points. The signatures of nontrivial topology are confirmed by the first-principles calculation, which shows an intricate parity inversion of bulk states. Our discoveries not only contribute to a better understanding of topological band structure in PtSe2 but also help further explore the exotic properties, as well as potential application, of group VIII transition-metal dichalcogenides.

Original languageEnglish (US)
Article number074202
JournalPhysical Review Materials
Issue number7
StatePublished - Dec 22 2017

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Physics and Astronomy (miscellaneous)


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