Dimensionality-dependent type-II Weyl semimetal state in Mo₀.₂₅W₀.₇₅Te₂

• Main Authors: Li, Peiling, Deng, Ya, Hsu, Chuang-Han, Zhu, Chao, Cui, Jian, Yang, Xue, Zhou, Jiadong, Hung, Yi-Chun, Fan, Jie, Ji, Zhongqing, Qu, Fanming, Shen, Jie, Yang, Changli, Jing, Xiunian, Lin, Hsin, Liu, Zheng, Lu, Li, Liu, Guangtong
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Materials; In-Plane Magnetic Fields; Electrical Transport Measurements
• Online Access: https://hdl.handle.net/10356/159394
• Institution: Nanyang Technological University

Weyl nodes and Fermi arcs in type-II Weyl semimetals (WSMs) have led to lots of exotic transport phenomena. Recently, Mo$_{0.25}$W$_{0.75}$Te$_{2}$ has been established as a type-II WSM with Weyl points located near Fermi level, which offers an opportunity to study its intriguing band structure by electrical transport measurements. Here, by selecting a special sample with the thickness gradient across two- (2D) and three-dimensional (3D) regime, we show strong evidences that Mo$_{0.25}$W$_{0.75}$Te$_{2}$ is a type-II Weyl semimetal by observing the following two dimensionality-dependent transport features: 1) A chiral-anomaly-induced anisotropic magneto-conductivity enhancement, proportional to the square of in-plane magnetic field (B$_{in}$$^{2}$); 2) An additional quantum oscillation with thickness-dependent phase shift. Our theoretical calculations show that the observed quantum oscillation originates from a Weyl-orbit-like scenario due to the unique band structure of Mo$_{0.25}$W$_{0.75}$Te$_{2}$. The in situ dimensionality-tuned transport experiment offers a new strategy to search for type-II WSMs.