Quantum Hall Effect of Weyl Fermions in Semiconducting n-type Tellurene

TL;DR

This paper reports the first experimental observation of Weyl fermions in a semiconductor, tellurene, revealing topological quantum Hall states and expanding Weyl physics into semiconducting materials.

Contribution

It demonstrates the existence of Weyl fermions in a semiconductor, tellurene, with topological properties evidenced by quantum Hall measurements, a novel finding in the field.

Findings

Observation of Weyl fermions in tellurene

Detection of topologically non-trivial pi Berry phase

Expansion of Weyl physics into semiconductors

Abstract

Dirac and Weyl nodal materials can host low-energy relativistic quasiparticles. Under strong magnetic fields, the topological properties of Dirac/Weyl materials can directly manifest through quantum Hall states. However, most Dirac/Weyl nodes generically exist in semimetals without exploitable bandgaps due to their accidental band-crossing origin. Here we report the first experimental observation of Weyl fermions in a semiconductor. Tellurene, the 2D form of tellurium, possesses 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 pi 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.