Polymorphism in Type-II Dirac Semimetal WSi₂ under Pressure: Structural, Mechanical, and Electronic Insights

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Physics

Background:

• Tungsten disilicide (WSi2) is recognized as a type-II Dirac candidate semimetal.
• Its unique electronic structure and robust mechanical properties make it suitable for electronic devices, quantum computing, and topological materials research.

Purpose of the Study:

• To synthesize high-quality WSi2 materials.
• To investigate the compressive behavior, structural, and electronic properties of WSi2 under high pressure.
• To understand the mechanisms behind its high-pressure stability and phase transitions.

Main Methods:

• In-situ high-pressure experiments were conducted.
• First-principles calculations were employed to complement experimental data.
• Systematic investigation of structural and electronic properties under varying pressures.

Main Results:

• WSi2 exhibits properties of a type-II Dirac semimetal.
• The material remains structurally stable under high pressure.
• An electronic phase transition from semimetal to metal occurs around 40 GPa, accompanied by a discontinuous softening of mechanical hardness.
• Strong hybridization of Si-3p and W-5d electrons contributes to structural stability.

Conclusions:

• The structural stability of WSi2 is attributed to strong electron hybridization, a rigid lattice, and an adaptable electronic structure.
• Pressure-induced electronic phase transition and mechanical softening are driven by energy band reconstruction and W-5d orbitals.
• This research offers critical insights into the high-pressure behavior of type-II Dirac semimetals, supporting their use in extreme condition applications.