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FRI: Friday Contributed Sessions
FRI 12: Quantum Phenomena in Solid-State Devices
FRI 12.5: Talk
Friday, September 12, 2025, 11:45–12:00, ZHG105
Interplay between Hund’s rule and Kondo effect in the third shell of a quantum dot — •Olfa Dani1, Johannes C. Bayer1,2, Timo Wagner1, Gertrud Zwicknagl3, and Rolf J. Haug1 — 1Institut für Festkörperphysik, Leibniz Universität Hannover, Hannover, Germany — 2Physikalisch-Technische Bundesanstalt, Braunschweig, Germany — 3Institut für Mathematische Physik, Technische Universität Braunschweig, Braunschweig, Germany
We study electron transport in the third shell [1] of a gate-defined quantum dot in a GaAs/AlGaAs two-dimensional electron gas. The device structure allows the precise determination and controlled variation of the number of electrons (N) occupying the quantum dot [2]. We observe zero-bias anomalies (ZBAs) with unexpected large widths for successive filling of the shell of the quantum dot. The ZBAs display a characteristic particle-hole symmetry for the three spin-degenerate orbital states. The broad widths of the ZBAs are attributed not only to the contribution of a Kondo resonance but also to the presence of excited Hund multiplets [3]. The role of Hund’s rule exchange is further supported by the triangular trend of the charging energy as function of N in the third shell. The quantum dot is viewed as a multi-orbital Kondo impurity with Hund’s interaction and serves as a model system for a Hund’s coupled impurity.
[1] L. P. Kouwenhoven, et. al., Rep. Prog. Phys. 64, 701-736 (2001).
[2] T. Wagner, et. al., Nat. Phys.15, 330-334 (2019).
[3] O. Dani, et. al., arXiv: 2505.21675 (2025).
Keywords: Quantum transport; Quantum dots; Coulomb blockade; Kondo effect