# Regensburg 2022 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 25: Poster 1

### HL 25.69: Poster

### Mittwoch, 7. September 2022, 18:00–20:00, P2

**Multi-Orbital Kondo Effect in Few-Electron Quantum Dots** — •Olfa Dani^{1}, Johannes Bayer^{1}, Timo Wagner^{1}, Gertrud Zwicknagl^{2}, and Rolf J. Haug^{1} — ^{1}Institut für Festkörperphysik, Leibniz Universität Hannover, Germany — ^{2}nstitut für Mathematische Physik, Technis- che 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.

We investigate a lateral quantum dot with a small number of electrons, formed electrostatically in a two-dimensional electron gas using top-gates. A quantum point contact was operated as a sensitive charge detector allowing the detection of single-electron tunneling through the system, which enables us to know the exact number of electrons N in the quantum dot. The latter is varied by changing the applied gate voltage.

For a strong coupling to the leads and possible symmetrical tunnel barriers, a Zero-bias anomaly (ZBA) is observed. This Kondo resonance appears for successive N showing a deviation from the conjectured odd-even behavior. The observed ZBA is strongest for N=9 and displays a particle-hole symmetry for N=7,..,11. It is absent for N=6 and N= 12. This observations indicate the influence of the shell structure of the electronic states in the quantum dot where orbital degeneracy is present.