Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 118: Surface Magnetism II (joint session O/MA)

O 118.1: Talk

Friday, March 20, 2020, 10:30–10:45, GER 38

Observation of tunable single-atom Yu-Shiba-Rusinov states — •Artem B. Odobesko¹, Domenico DiSante², Alexander Kowalski², Felix Friedrich¹, Ronny Thomale², Giorgio Sangiovanni², and Matthias Bode¹ — ¹Physikalisches Institut, Universität Würzburg, Am Hubland, Würzburg, Germany — ²Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, Würzburg, Germany

Through scanning tunneling spectroscopy, we analyze the interdependence of Kondo screening and superconductivity. Our data obtained on single Fe adatoms on Nb(110) show that the coupling and the resulting Yu-Shiba-Rusinov (YSR) bound states are strongly adsorption site-dependent and exhibit a quantum phase transition, where two YSR resonances cross at zero bias. By sweeping the external magnetic field to turn off and on superconductivity in the Nb substrate, we were able to study the interaction of individual magnetic adatoms with the normal-metallic or superconducting substrate in two consecutive experiments. The data show that the in-gap position of YSR states scales with the Kondo temperature and exhibits a cross-over at 0.7 Δ, in good agreement with theoretically predicted value. The observed experimental signatures are rationalized by combined density functional theory and continuous-time quantum Monte-Carlo calculations. This treatment shows that the size of the magnetic moment and the hybridization of the impurity orbitals with the substrate are key parameters for understanding the interaction between magnetic adatoms and superconductors.