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Kondo effect in carbon nanotube quantum dots with spin-orbit coupling
Tie-Feng Fang1, Wei Zuo, Hong-Gang Luo
1Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Physical Review Letters
|December 31, 2008
Summary
Spin-orbit coupling in carbon nanotube quantum dots breaks SU(4) symmetry, splitting the Kondo resonance. This effect, influenced by magnetic fields, reveals multipeak structures and predicts a novel orbital Kondo effect.
Area of Science:
- Condensed Matter Physics
- Quantum Dots
- Spintronics
Background:
- Recent experiments observed spin-orbit coupling in carbon nanotube quantum dots.
- The Kondo effect in quantum dots is a many-body phenomenon sensitive to symmetries.
Purpose of the Study:
- Investigate the influence of spin-orbit coupling on the Kondo effect in carbon nanotube quantum dots.
- Analyze the interplay between spin-orbit coupling and Zeeman effects under magnetic fields.
Main Methods:
- Theoretical investigation of electron behavior in quantum dots.
- Analysis of symmetry breaking and resonance splitting.
- Microscopic cotunneling process identification.
Main Results:
- Spin-orbit coupling intrinsically lifts degeneracy, breaking SU(4) symmetry and splitting the Kondo resonance at zero magnetic field.
- Applied magnetic fields cause further splitting and fine multipeak structures due to spin-orbit coupling and Zeeman effects.
- Each Kondo peak's microscopic cotunneling process is uniquely identified.
Conclusions:
- Spin-orbit coupling significantly modifies the Kondo effect in carbon nanotube quantum dots.
- The study predicts a purely orbital Kondo effect in the two-electron regime.
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