Skew Scattering and Side Jump Drive Exciton Valley Hall Effect in Two-Dimensional Crystals

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• The exciton valley Hall effect describes the spatial separation of excitons based on their valley properties.
• This phenomenon is typically linked to anomalous velocity caused by Berry curvature in Bloch bands.

Purpose of the Study:

• To demonstrate that anomalous velocity is not the driving mechanism behind the exciton valley Hall effect.
• To investigate the roles of side-jump and skew scattering in this effect.
• To develop a microscopic theory for the exciton valley Hall effect under synthetic electric fields and phonon drag.

Main Methods:

• Development of a microscopic theory for the exciton valley Hall effect.
• Calculation of contributions to the valley Hall current.
• Demonstration of anomalous velocity cancellation.
• Extension of the drift-diffusion model to include the valley Hall effect.

Main Results:

• Anomalous velocity does not govern the exciton valley Hall effect; side-jump and skew scattering are the key mechanisms.
• The theory accounts for contributions from synthetic electric fields and phonon drag.
• The study highlights the sensitivity of the effect to the drag force origin and scattering processes.
• Exciton density and valley polarization profiles were calculated using the extended drift-diffusion model.

Conclusions:

• The exciton valley Hall effect is primarily driven by side-jump and skew scattering mechanisms.
• A comprehensive theoretical framework has been established to understand and model this effect.
• The findings offer new insights into controlling and manipulating valley-dependent phenomena in excitonic systems.