Pressure‐Induced Phase Transition in Weyl Semimetallic WTe2

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 13; no. 40
• Main Authors: Xia, Juan, Li, Dong‐Fei, Zhou, Jia‐Dong, Yu, Peng, Lin, Jun‐Hao, Kuo, Jer‐Lai, Li, Hai‐Bo, Liu, Zheng, Yan, Jia‐Xu, Shen, Ze‐Xiang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 25.10.2017
• Subjects: first‐principles calculations; Giant magnetoresistance; high pressure; Magnetic properties; Magnetoresistance; Magnetoresistivity; Nanotechnology; phase transition; Phase transitions; Raman spectroscopy; Red shift; Single crystals; Structural stability; Superconductivity; Switching; Tungsten; tungsten ditelluride
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201701887

Tungsten ditelluride (WTe2) is a semimetal with orthorhombic Td phase that possesses some unique properties such as Weyl semimetal states, pressure‐induced superconductivity, and giant magnetoresistance. Here, the high‐pressure properties of WTe2 single crystals are investigated by Raman microspectroscopy and ab initio calculations. WTe2 shows strong plane‐parallel/plane‐vertical vibrational anisotropy, stemming from its intrinsic Raman tensor. Under pressure, the Raman peaks at ≈120 cm−1 exhibit redshift, indicating structural instability of the orthorhombic Td phase. WTe2 undergoes a phase transition to a monoclinic T′ phase at 8 GPa, where the Weyl states vanish in the new T′ phase due to the presence of inversion symmetry. Such Td to T′ phase transition provides a feasible method to achieve Weyl state switching in a single material without doping. The new T′ phase also coincides with the appearance of superconductivity reported in the literature. The plane‐parallel/plane‐vertical vibrational anisotropies of WTe2 single crystal under high pressure are investigated by Raman spectroscopy and ab initio calculations. WTe2 undergoes a phase transition from orthorhombic Td to monoclinic T′ phase at 8 GPa, where the Weyl states vanish in the new T′ phase due to the presence of inversion symmetry.