Spectroscopic evidence for bulk-band inversion and three-dimensional massive Dirac fermions in ZrTe5

Title

Spectroscopic evidence for bulk-band inversion and three-dimensional massive Dirac fermions in ZrTe5

 Author

Chen, Zhi Guo (Chinese Academy of Sciences)
Chen, R. Y. (Peking University)
Zhong, R. D. (Brookhaven National Laboratory)
Schneeloch, John (Brookhaven National Laboratory)
Zhang, C. (Brookhaven National Laboratory)
Huang, Y. (Brookhaven National Laboratory)
Qu, F. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech; Chinese Academy of Sciences)
Yu, R. (Wuhan University)
Li, Q. (Brookhaven National Laboratory)
Gu, G. D. (Brookhaven National Laboratory)
Wang, N. L. (Peking University; Collaborative Innovation Center of Quantum Matter)

Faculty

QuTech

 Date

2017

 Abstract

Three-dimensional topological insulators (3D TIs) represent states of quantum matters in which surface states are protected by timereversal symmetry and an inversion occurs between bulk conduction and valence bands. However, the bulk-band inversion, which is intimately tied to the topologically nontrivial nature of 3D Tis, has rarely been investigated by experiments. Besides, 3D massive Dirac fermions with nearly linear band dispersions were seldom observed in TIs. Recently, a van der Waals crystal, ZrTe5, was theoretically predicted to be a TI. Here, we report an infrared transmission study of a high-mobility [∼33,000 cm2/(V · s)] multilayer ZrTe5 flake at magnetic fields (B) up to 35 T. Our observation of a linear relationship between the zero-magnetic-field optical absorption and the photon energy, a bandgap of ∼10 meV and a √B dependence of the Landau level (LL) transition energies at low magnetic fields demonstrates 3D massive Dirac fermions with nearly linear band dispersions in this system. More importantly, the reemergence of the intra-LL transitions at magnetic fields higher than 17 T reveals the energy cross between the two zeroth LLs, which reflects the inversion between the bulk conduction and valence bands. Our results not only provide spectroscopic evidence for the TI state in ZrTe5 but also open up a new avenue for fundamental studies of Dirac fermions in van der Waals materials.


 Subject

Band inversion
Dirac fermions
Landau levels
Topological insulators
Zeeman splitting

 To reference this document use:

http://resolver.tudelft.nl/uuid:11d69060-4deb-407e-8def-92b3f8440650

 DOI

https://doi.org/10.1073/pnas.1613110114

 Embargo date

2018-07-31

 ISSN

0027-8424

 Source

Proceedings of the National Academy of Sciences of the United States of America, 114 (5), 816-821

 Part of collection

Institutional Repository

 Document type

journal article

 Rights

© 2017 Zhi Guo Chen, R. Y. Chen, R. D. Zhong, John Schneeloch, C. Zhang, Y. Huang, F. Qu, R. Yu, Q. Li, G. D. Gu, N. L. Wang
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