Topological Lifshitz transition and one-dimensional Weyl mode in HfTe5

• Published in: Nature materials Vol. 22; no. 1; pp. 84 - 91
• Main Authors: Wu, Wenbin, Shi, Zeping, Du, Yuhan, Wang, Yuxiang, Qin, Fang, Meng, Xianghao, Liu, Binglin, Ma, Yuanji, Yan, Zhongbo, Ozerov, Mykhaylo, Zhang, Cheng, Lu, Hai-Zhou, Chu, Junhao, Yuan, Xiang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2023; Nature Publishing Group
• Subjects: 639/766/119/2792/4128; 639/766/119/995; Biomaterials; Chemistry and Materials Science; Condensed Matter Physics; Crystals; Electron states; Elementary excitations; Energy; Infrared spectroscopy; Infrared tracking; Laboratories; Level crossings; Magnetic fields; Materials Science; Nanotechnology; Optical and Electronic Materials; Phase transitions; Physics; Spectrum analysis; Topological insulators
• ISSN: 1476-1122; 1476-4660; 1476-4660
• DOI: 10.1038/s41563-022-01364-5

Landau band crossings typically stem from the intra-band evolution of electronic states in magnetic fields and enhance the interaction effect in their vicinity. Here in the extreme quantum limit of topological insulator HfTe 5 , we report the observation of a topological Lifshitz transition from inter-band Landau level crossings using magneto-infrared spectroscopy. By tracking the Landau level transitions, we demonstrate that band inversion drives the zeroth Landau bands to cross with each other after 4.5 T and forms a one-dimensional Weyl mode with the fundamental gap persistently closed. The unusual reduction of the zeroth Landau level transition activity suggests a topological Lifshitz transition at 21 T, which shifts the Weyl mode close to the Fermi level. As a result, a broad and asymmetric absorption feature emerges due to the Pauli blocking effect in one dimension, along with a distinctive negative magneto-resistivity. Our results provide a strategy for realizing one-dimensional Weyl quasiparticles in bulk crystals. The manuscript reports on the experimental observation of a Lifshitz transition in a topological insulator HfTe 5 subject to a strong magnetic field, which results in the formation of topological one-dimensional Weyl modes in the bulk of a three-dimensional material.