Valley polarization assisted spin polarization in two dimensions.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Valleytronics utilizes electron valley polarization to modify physical properties in 2D systems.
• Electron-electron interactions in valley-polarized systems lead to phenomena like the fractional quantum Hall effect.
• Understanding spin alignment in magnetic fields is crucial for valleytronics applications.

Purpose of the Study:

• To investigate electron spin alignment in magnetic fields within valley-polarized silicon-on-insulator quantum wells.
• To compare spin polarization behavior in valley-polarized versus valley-degenerate systems.
• To explore the role of electron-electron interactions in these phenomena.

Main Methods:

• Experimental measurements of electron spin alignment in silicon-on-insulator quantum wells.
• Application of magnetic fields to induce spin polarization.
• Parameter-free ab initio quantum Monte Carlo simulations for theoretical validation.

Main Results:

• Less magnetic field is required to fully spin polarize a valley-polarized system compared to a valley-degenerate one.
• Experimental observations are quantitatively supported by quantum Monte Carlo simulations.
• The findings indicate greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystallization.

Conclusions:

• The study reveals counterintuitive spin polarization behavior in valley-polarized silicon quantum wells.
• Results suggest the existence of a novel strongly correlated electron liquid at low electron densities.
• This work advances the understanding of electron interactions and spin dynamics in emerging valleytronic devices.