SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 24: Quantum Dots: Transport (joint session HL/TT)
TT 24.4: Vortrag
Dienstag, 28. März 2023, 10:15–10:30, POT 151
Multi-Channel Kondo Effect in Few-Electron Quantum Dots — •Olfa Dani1, Johannes C. Bayer1, Timo Wagner1, Gertrud Zwicknagl2, and Rolf J. Haug1 — 1Institut für Festkörperphysik, Leibniz Universität Hannover, Germany — 2Institut für Mathematische Physik, Technische Universität Braunschweig, Germany
The Kondo effect is a many particle entangled system, that involves the interaction between a localized spin in the quantum dot and free electrons in the electron reservoirs. This entanglement can be calculated using simplifying assumptions concerning the electronic structure of the quantum dot.
In this work we investigate a quantum dot device formed electrostatically in a two-dimensional electron gas using top-gates. A quantum point contact is used as a sensitive charge detector to detect single-electrons tunneling through the system. This enables us to know the exact number of electrons in the quantum dot (Ne). By changing the applied gate voltage, we are able to control Ne.
A Zero-bias anomaly is observed for a strong coupling to the leads and possible symmetrical tunnel barriers. This Kondo resonance appears for successive Ne showing a deviation from the conjectured odd-even behavior. The Kondo resonance is strongest for Ne=9 and displays a particle-hole symmetry for Ne =7,..,11. It is absent for Ne =6 and Ne = 12. These observations indicate the influence of the shell structure [1] of the electronic states in the quantum dot where orbital degeneracy is present.
[1] L. P. Kouwenhoven, et. al., Rep. Prog. Phys. 64, 701-736 (2001).