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Nonequilibrium Zeeman splitting in quantum transport through nanoscale junctions.
Sebastian Schmitt1, Frithjof B Anders
1Lehrstuhl für Theoretische Physik II, Technische Universität Dortmund, Otto-Hahn-Strasse 4, 44221 Dortmund, Germany.
Physical Review Letters
|August 27, 2011
Summary
We studied quantum dot conductance in a magnetic field. The Zeeman splitting behavior changes significantly with correlations and magnetic field strength, revealing a crossover in its dependence on device asymmetry.
Area of Science:
- Condensed Matter Physics
- Quantum Information Science
Background:
- Understanding electron transport in quantum dots is crucial for quantum computing and spintronics.
- The Kondo effect in quantum dots exhibits complex behavior under magnetic fields and varying correlations.
Purpose of the Study:
- To investigate the differential conductance (G(V)) of a quantum dot subjected to an external magnetic field.
- To analyze the influence of electron correlations and device asymmetry on Zeeman splitting.
Main Methods:
- Utilizing a Keldysh conserving approximation for weakly correlated systems.
- Employing the scattering-states numerical renormalization group (NRG) for intermediate and strongly correlated regimes out of equilibrium.
Main Results:
- In weakly correlated regimes, Zeeman splitting in G(V) is highly sensitive to device asymmetry.
- In strongly correlated regimes, the Zeeman-split zero-bias anomaly position (Δ(K)) shows independence from asymmetry and Zeeman energy (Δ(0)).
- Observed a crossover from spin-fluctuation dominated Kondo regime (Δ(K)<Δ(0)) to charge-fluctuation induced larger splittings (Δ(K)>Δ(0)) at higher magnetic fields.
Conclusions:
- The study reveals distinct behaviors of Zeeman splitting in quantum dots based on correlation strength and magnetic field.
- Findings explain experimental observations of crossovers in Kondo physics under magnetic fields.
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