Tungsten ditelluride (WTe₂) is a semimetal with orthorhombic T_d 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 T_d 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 T_d 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.

中文翻译：

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Weyl半金属WTe2中的压力诱导相变

二碲化钨（WTe ₂）是具有正交晶系T _d相的半金属，具有一些独特的特性，例如Weyl半金属态，压力感应超导性和巨大的磁阻。在此，通过拉曼光谱和从头算计算研究了WTe ₂单晶的高压特性。WTe ₂表现出很强的平面平行/平面垂直振动各向异性，这源于其固有的拉曼张量。在压力下，≈120cm ^-1处的拉曼峰出现红移，表明斜方晶系T _d相的结构不稳定性。WTe ₂在8 GPa时经历单相T'相的转变，由于反对称的存在，Weyl状态在新的T'相中消失。这种从T _d到T'的相变提供了一种在不掺杂的情况下在单一材料中实现Weyl状态转换的可行方法。新的T'相也与文献中报道的超导现象相吻合。