Valley polarization in Si(100) at zero magnetic field

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Materials Science

Background:

• Degeneracy of valley states in silicon quantum wells is a fundamental property.
• Understanding valley dynamics is crucial for developing advanced semiconductor devices.

Purpose of the Study:

• To investigate and directly observe valley splitting in a SiO(2)/Si(100)/SiO(2) quantum well.
• To determine the temperature and magnetic field dependence of valley splitting and polarization.

Main Methods:

• Transport measurements were conducted on a silicon quantum well structure.
• Conductance was analyzed to identify signatures of valley splitting.

Main Results:

• Valley splitting was directly observed as a distinct step in conductance.
• This step demarcates regions of valley-unpolarized and valley-polarized electron states.
• Valley splitting and polarization were found to persist above liquid helium temperatures and are independent of magnetic field.

Conclusions:

• Single-particle valley splitting and valley polarization are intrinsic properties of (100) silicon quantum wells.
• These effects are present even at zero magnetic field and elevated temperatures.
• The findings have implications for spintronic and quantum computing applications utilizing silicon.