SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 81: Poster Session VI: Poster to Mini-Symposium: Manipulation and control of spins on functional surfaces II
O 81.3: Poster
Mittwoch, 3. März 2021, 13:30–15:30, P
Experimental connection between Yu-Shiba-Rusinov states and the Kondo effect using numerical renormalization group theory — •Haonan Huang1, Sujoy Karan1, Robert Drost1, Ciprian Padurariu2, Alfredo Levy Yeyati3, Juan Carlos Cuevas3, Björn Kubala2, Joachim Ankerhold2, Klaus Kern1,4, and Christian R. Ast1 — 1MPI für Festkörperforschung, Stuttgart, Germany — 2Institut für Komplexe Quantensysteme and IQST, Universität Ulm, Ulm, Germany — 3IFIMAC, Universidad Autónoma de Madrid, Madrid, Spain — 4EPFL, Lausanne, Switzerland
Magnetic impurities on superconductors give rise to Yu-Shiba-Rusinov (YSR) states in the gap. When the superconductivity is quenched, the Kondo effect manifests itself as a spectral anomaly at the Fermi energy. Both phenomena can be understood quantitatively with the single impurity Anderson model (SIAM) using numerical renormalization group (NRG) theory. One prediction of this theory is that the YSR energy depends universally on the ratio between the Kondo temperature TK and the superconducting order parameter Δ. Nevertheless, deviations from this universal behavior have been observed in different experiments. Using a scanning tunneling miscroscope, we show that for a spin 1/2 impurity on the apex of a superconducting vanadium tip, both the YSR state and the Kondo peak can be quantitatively reproduced by the NRG theory using the Ljubljana code. Intriguingly, the asymmetry of the experimental spectra is also contained within the SIAM for both cases, indicating the essential role of the particle-hole asymmetry which is absent in the conventional Kondo impurity model.