Polymorphism\nin Type-II Dirac Semimetal WSi<sub>2</sub> under Pressure: Structural,\nMechanical, and Electronic Insights

The type-II Dirac candidate semimetal WSi<sub>2</sub> is a promising\ncandidate for electronic devices, quantum computing, and topological\nmaterials research, owing its distinct electronic structure and superior\nmechanical properties. Here, we synthesized high-quality WSi<sub>2</sub> materials and systematically investigated their compressive behavior,\nand structural and electronic properties under high pressure using\nin-situ high pressure experiments, complemented by first-principles\ncalculations. The results confirms that WSi<sub>2</sub> has the properties\nof a type-II Dirac semimetal. Our results demonstrate that WSi<sub>2</sub> maintains structural stability under high pressure but undergoes\nan electronic phase transition from a semimetal to a metal around\n40 GPa. Additionally, the mechanical hardness softens discontinuously\nat this pressure. The structural stability of WSi<sub>2</sub> under\nhigh pressure is attributed to the strong hybridization of Si-3<i>p</i> and W-5<i>d</i> electrons, the rigid crystal\nlattice, and the adaptable electronic structure. The pressure-induced\nelectronic phase transition and softening are primarily governed by\nthe energy band reconstruction and W-5<i>d</i> orbitals.\nThis study provides valuable insights into the high-pressure behavior\nof type-II Dirac semimetal, highlighting their potential for advanced\napplications in electronic devices and topological quantum computing\nunder extreme conditions by elucidating their structural stability\nand electronic phase transition mechanisms.