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Spin and polarized current from Coulomb blockaded quantum dots.
R M Potok1, J A Folk, C M Marcus
1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Physical Review Letters
|August 9, 2003
Summary
We measured spin transitions in GaAs quantum dots. Emitted current spin polarization aligns with magnetic fields, independent of the quantum dot
Area of Science:
- Semiconductor quantum dots
- Spintronics
- Quantum transport
Background:
- Understanding spin behavior in semiconductor nanostructures is crucial for quantum technologies.
- Gallium arsenide (GaAs) quantum dots offer a tunable platform for studying electron spin dynamics.
Purpose of the Study:
- To investigate spin transitions in GaAs quantum dots within the Coulomb blockade regime.
- To correlate transport spectroscopy measurements with direct spin polarization measurements of emitted current.
Main Methods:
- Utilizing transport spectroscopy to probe ground and excited states of GaAs quantum dots.
- Employing spin-sensitive electron focusing to measure the spin polarization of emitted current.
- Analyzing data to determine spin-increasing/decreasing transitions and measure g-factors.
Main Results:
- Transport spectroscopy identified spin-increasing and spin-decreasing transitions, along with higher-spin ground states.
- Accurate g-factors were measured, even for single-electron spin states.
- Emitted current spin polarization consistently aligned with the applied magnetic field, irrespective of the ground state spin transition.
Conclusions:
- The study provides detailed insights into spin dynamics in GaAs quantum dots.
- Direct measurement confirms that emitted current spin polarization is dictated by the magnetic field, not the internal spin state.
- Findings are significant for developing spin-based quantum devices.