Interlayer-coupling-engineerable flat bands in twisted MoSi₂N₄bilayers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Two-dimensional (2D) layered materials offer unique electronic and mechanical properties.
• Molybdenum disilicide nitride (MoSi2N4) is a recently synthesized 2D semiconductor with notable strength, stability, and conductivity.
• Understanding the electronic behavior of stacked 2D materials is crucial for novel device applications.

Purpose of the Study:

• Investigate the impact of twist angle and interlayer distance on the electronic properties of twisted bilayer MoSi2N4.
• Determine the conditions under which flat bands emerge in this material.
• Propose methods for controlling these electronic properties.

Main Methods:

• Utilized first-principles calculations to model twisted bilayer MoSi2N4.
• Analyzed the electronic band structure as a function of twist angle (θ) and interlayer distance.
• Simulated the effect of hydrostatic pressure on interlayer spacing.

Main Results:

• Flat bands are absent in twisted bilayer MoSi2N4 below a critical twist angle of 3.89°.
• For a twist angle of 5.09°, flat bands emerge as the interlayer distance is reduced.
• Hydrostatic pressure effectively modulates the interlayer distance, influencing the formation of flat bands.

Conclusions:

• Hydrostatic pressure serves as a tunable parameter for engineering flat bands in twisted bilayer MoSi2N4.
• The findings provide a theoretical basis for exploring MoSi2N4 in strong correlation physics and superconductivity.
• This research opens avenues for designing novel electronic devices based on tailored 2D materials.