Large valley splitting induced by spin-orbit coupling effects in monolayer W₂NSCl

Area of Science:

• Materials Science
• Condensed Matter Physics
• Quantum Information

Background:

• Two-dimensional (2D) valley materials are crucial for advanced information storage and processing.
• Developing materials with significant valley splitting is key for spintronics and valley electronics.

Purpose of the Study:

• To theoretically design novel 2D materials, specifically W₂NSCl MXenes, with substantial valley splitting.
• To investigate the potential of these materials for spintronics and valley electronics.

Main Methods:

• First-principle calculations were employed to design and analyze the W₂NSCl monolayer.
• Analysis included spin-orbit coupling (SOC), broken inversion symmetry, and Rashba effect.
• Berry curvature and its dependence on strain were calculated using Wannier function localization.

Main Results:

• The W₂NSCl monolayer demonstrated large valley splitting: 491 meV (valence bands) and 83 meV (conduction bands) at K/K'.
• The material exhibits robustness to biaxial strain and a significant Rashba effect (1.019 V Å) due to broken mirror symmetry.
• Non-zero Berry curvature was observed at K/K', increasing monotonically with applied strain (-4% to 4%).

Conclusions:

• W₂NSCl MXenes are identified as promising candidates for next-generation valley electronics and spintronics.
• The material's properties, including large valley splitting and strain-tunable Berry curvature, support its potential applications.