Dirac and Weyl nodal materials can host low-energy relativistic quasiparticles. Under strong magnetic fields, the topological properties of Dirac/Weyl materials can directly be observed through quantum Hall states. However, most Dirac/Weyl nodes generically exist in semimetals without exploitable band gaps due to their accidental band-crossing origin. Here, we report the first experimental observation of Weyl fermions in a semiconductor. Tellurene, the two-dimensional form of tellurium, possesses a chiral crystal structure which induces unconventional Weyl nodes with a hedgehog-like radial spin texture near the conduction band edge. We synthesize high-quality n-type tellurene by a hydrothermal method with subsequent dielectric doping and detect a topologically non-trivial π Berry phase in quantum Hall sequences. Our work expands the spectrum of Weyl matter into semiconductors and offers a new platform to design novel quantum devices by marrying the advantages of topological materials to versatile semiconductors.
The data that supports the argument and generates the plots in this paper are available from the corresponding author upon reasonable request.
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P.D.Y. was supported by NSF/AFOSR 2DARE programmes ARO and SRC. W.W. acknowledges the College of Engineering and School of Industrial Engineering at Purdue University for the startup support. W.W. was partially supported by a grant from the Oak Ridge Associated Universities (ORAU) Junior Faculty Enhancement Award Programme. W.W. and P.D.Y. were also supported by NSF under grant no. CMMI-1762698. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-1644779 and the State of Florida. G.Q. and C.N. acknowledge technical support from National High Magnetic Field Laboratory staff J. Jaroszynski, A. Suslov and W. Coniglio. The authors want to give special thanks to K. von Klitzing, T. Ando, W. Pan, K. Chang, F. Zhang, C. Liu, K. Cho, Y. Nie and J. Hwang for the insightful discussions on electronic structures of Te. The authors also acknowledge A. R. Charnas for editorial assistance.
The authors declare no competing interests.
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