Twist angle-dependent valley polarization switching in heterostructures.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Moiré superlattices in transition metal dichalcogenide heterostructures offer control over valley physics.
• Interlayer excitons (IXs) exhibit valley properties crucial for valleytronics.
• Electrical control of valley polarization in these systems remains underexplored.

Purpose of the Study:

• Investigate the twist angle-dependent control of excitonic potential on valley polarization.
• Elucidate the physical mechanisms governing twist angle modulation of valley polarization.
• Demonstrate electrically controlled valley-addressable devices.

Main Methods:

• Fabrication of van der Waals heterostructures with controlled twist angles.
• Electrical gating to modulate carrier densities and exciton properties.
• Optical spectroscopy to probe valley polarization and exciton dynamics.

Main Results:

• Demonstrated dependence of polarization switching and degree of valley polarization on moiré period.
• Identified mechanisms for twist angle modulation of exciton potential and electron-hole exchange interaction.
• Achieved twist angle-dependent valley polarization of IXs.

Conclusions:

• Twist angle engineering effectively manipulates valley polarization of IXs in electrically controlled heterostructures.
• The findings provide a pathway for electrical control of valley degrees of freedom in twistronic devices.
• This work paves the way for next-generation valleytronic devices with tunable properties.