Quantum Hall effect of Weyl fermions in n-type semiconducting tellurene

• Published in: Nature nanotechnology Vol. 15; no. 7; pp. 585 - 591
• Main Authors: Qiu, Gang, Niu, Chang, Wang, Yixiu, Si, Mengwei, Zhang, Zhuocheng, Wu, Wenzhuo, Ye, Peide D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2020; Nature Publishing Group
• Subjects: 639/301/1005/1007; 639/301/119/2794; 639/925/357/1018; Chemistry and Materials Science; Conduction; Conduction bands; Crystal structure; Electrons; Elementary excitations; Energy gap; Fermions; Hydrothermal crystal growth; Magnetic fields; Magnetic properties; Materials Science; Metalloids; N-type semiconductors; Nanotechnology; Nanotechnology and Microengineering; Nodes; Quantum Hall effect; Quantum mechanics; Relativistic effects; Semiconductors; Tellurium; Topology
• DOI: 10.1038/s41565-020-0715-4
• ISSN: 1748-3387; 1748-3395

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 accidental band-crossing origin of Weyl nodes paired with the absence of sizeable band gaps hampers the exploitation of low-energy relativistic quasiparticles in Weyl semimetals. In a gate-tunable high-quality tellurene film, quantum Hall measurements unveil a topologically non-trivial π Berry phase caused by unconventional Weyl nodes in these tellurium two-dimensional sheets.