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Coulomb-induced Rashba spin-orbit coupling in semiconductor quantum wells
1Department of Physics, University of Missouri-Columbia, Columbia, Missouri 65211, USA.
Physical Review Letters
|September 28, 2010
Summary
This study designs a semiconductor quantum well where electrons conserve spin at low voltages but experience spin relaxation above a threshold voltage due to Rashba spin-orbit interaction.
Area of Science:
- Condensed matter physics
- Semiconductor spintronics
Background:
- The Rashba spin-orbit interaction (SOI) in two-dimensional electron gases (2DEGs) is crucial for spintronic applications.
- In the absence of external fields, SOI originates from the screened electrostatic potential of ionized donors.
Purpose of the Study:
- To engineer a quantum well structure that controls electron spin dynamics.
- To create a tunable spin relaxation mechanism based on the Dyakonov-Perel model.
Main Methods:
- Designing quantum well wave functions to differentiate spin behavior in subbands.
- Investigating electron spin projection (s(z)) under varying applied voltages.
Main Results:
- Electrons in the lowest subband maintain their spin projection along the growth axis (s(z)).
- Electrons in the second subband exhibit spin precession due to Rashba SOI.
- A threshold voltage (V*) was identified, below which spin is conserved and above which Dyakonov-Perel spin relaxation is activated.
Conclusions:
- A specially designed quantum well can act as a tunable spin relaxation trigger.
- This control over spin relaxation is voltage-dependent, offering potential for spintronic devices.
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