Stress-driven structural and bond reconstruction in 2D ferromagnetic semiconductor VSe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) transition metal dichalcogenides are crucial for high-performance electronic, spintronic, and optoelectronic devices.
• Room-temperature ferromagnetism and semiconduction in 2D VSe2 were previously linked to its stable 2H-phase.

Purpose of the Study:

• To investigate the formation of a metastable semiconducting H' phase of VSe2 from the H phase using first-principles calculations.
• To explore the effects of uniaxial stress or strain on the stability, magnetic properties, and electronic structure of VSe2 phases.

Main Methods:

• First-principles calculations were employed to study the structural, dynamical, and electronic properties of VSe2.
• Phonon spectra calculations were used to determine the dynamical stability of the H' phase.
• Analysis of spin-resolved electronic structures, band edges, and effective carrier masses under stress/strain.

Main Results:

• A metastable semiconducting H' phase of VSe2 can be formed from the H phase via uniaxial stress or strain.
• The H' phase exhibits enhanced ferromagnetism and an increased Curie temperature under applied stress/strain.
• Uniaxial stress/strain significantly alters electronic structures, band edges, and carrier masses, potentially creating flat bands in the H' phase.

Conclusions:

• Structural and bond reconstruction in 2D VSe2 can be achieved through uniaxial stress, leading to the metastable H' phase.
• The H' phase demonstrates improved ferromagnetic properties and tunable electronic characteristics.
• This work provides a pathway for engineering 2D ferromagnetic semiconductors for advanced spintronic and optoelectronic applications.