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Interplay between the mesoscopic Stoner and Kondo effects in quantum dots
1Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055, USA.
Physical Review Letters
|May 21, 2005
Summary
We found a new regime where Kondo correlations are enhanced near the Stoner transition. In this regime, a Zeeman field surprisingly boosts the Kondo scale, unlike in noninteracting systems.
Area of Science:
- Condensed matter physics
- Quantum mechanics
Background:
- Electrons in quantum dots can exhibit Kondo correlations with magnetic impurities.
- Ferromagnetic interactions among electrons can lead to a Stoner transition.
Purpose of the Study:
- To investigate the interplay between ferromagnetic electron-electron interactions and antiferromagnetic impurity interactions in a quantum dot.
- To identify novel Kondo correlation regimes and their unique signatures.
Main Methods:
- Numerical simulations of interacting electrons in a quantum dot.
- Analysis of the Kondo effect under varying interaction strengths (J) and external magnetic fields (Zeeman field).
Main Results:
- A Stoner-enhanced Kondo regime emerges as J approaches 1.
- In this regime, the Kondo scale increases with increasing Zeeman field, contrary to standard behavior.
- Beyond this regime, the Kondo effect is suppressed, and the impurity spin flips.
Conclusions:
- The Stoner transition significantly modifies Kondo physics in quantum dots.
- The Zeeman-field-enhanced Kondo scale is a key experimental signature of this novel regime.
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