Lorentz-violating type-II Dirac fermions in transition metal dichalcogenide PtTe2

• Published in: Nature communications Vol. 8; no. 1; pp. 1 - 6
• Main Authors: Yan, Mingzhe, Huang, Huaqing, Zhang, Kenan, Wang, Eryin, Yao, Wei, Deng, Ke, Wan, Guoliang, Zhang, Hongyun, Arita, Masashi, Yang, Haitao, Sun, Zhe, Yao, Hong, Wu, Yang, Fan, Shoushan, Duan, Wenhui, Zhou, Shuyun
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15.08.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/2792; 639/766/119/995; Chalcogenides; Condensed matter physics; Cones; Fermions; High energy physics; Humanities and Social Sciences; multidisciplinary; Phase transitions; Physics; Science; Science (multidisciplinary); Spectroscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-00280-6

Topological semimetals have recently attracted extensive research interests as host materials to condensed matter physics counterparts of Dirac and Weyl fermions originally proposed in high energy physics. Although Lorentz invariance is required in high energy physics, it is not necessarily obeyed in condensed matter physics, and thus Lorentz-violating type-II Weyl/Dirac fermions could be realized in topological semimetals. The recent realization of type-II Weyl fermions raises the question whether their spin-degenerate counterpart—type-II Dirac fermions—can be experimentally realized too. Here, we report the experimental evidence of type-II Dirac fermions in bulk stoichiometric PtTe 2 single crystal. Angle-resolved photoemission spectroscopy measurements and first-principles calculations reveal a pair of strongly tilted Dirac cones along the Γ-A direction, confirming PtTe 2 as a type-II Dirac semimetal. Our results provide opportunities for investigating novel quantum phenomena (e.g., anisotropic magneto-transport) and topological phase transition. Whether the spin-degenerate counterpart of Lorentz-violating Weyl fermions, the Dirac fermions, can be realized remains as an open question. Here, Yan et al. report experimental evidence of such type-II Dirac fermions in bulk PtTe 2 single crystal with a pair of strongly tilted Dirac cones.