Collective spin Hall effect for electron-hole gratings.

Area of Science:

• Condensed matter physics
• Quantum mechanics
• Materials science

Background:

• Electron-hole gratings in quantum wells are crucial for optoelectronic devices.
• The electronic spin Hall effect (SHE) is a key phenomenon in spintronics.
• Understanding spin-charge coupling is vital for advanced quantum technologies.

Purpose of the Study:

• To investigate the generation of spin gratings via the electronic spin Hall effect in GaAs quantum wells.
• To explore the phenomenon termed the "collective spin Hall effect" (CSHE).
• To analyze the coupled spin-charge dynamics and their influence on spin density evolution.

Main Methods:

• Applying an electric field parallel to the wave fronts of an electron-hole grating.
• Utilizing a GaAs quantum well as the experimental system.
• Conducting a detailed study of coupled spin-charge dynamics in quantum wells with varying growth directions.

Main Results:

• An electric field parallel to the wave fronts induces a spin grating with the same wave vector.
• The amplitude of the induced spin grating can exceed 1% of the initial density grating.
• Observed rich features in spin density time evolution, including the generation of helical spin gratings.

Conclusions:

• The collective spin Hall effect provides a novel mechanism for generating spin gratings.
• The findings offer insights into controlling spin density in quantum wells.
• The potential for generating helical spin gratings opens new avenues for spintronic applications.