SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Spins on Surfaces at the Atomic Scale I
O 7.1: Topical Talk
Montag, 27. März 2023, 10:30–11:00, REC C 213
Superconductivity in atom-by-atom crafted quantum corrals — •Lucas Schneider1, Khai That Ton1, Ioannis Ioannidis2,3, Jannis Neuhaus-Steinmetz1, Thore Posske2,3, Roland Wiesendanger1, and Jens Wiebe1 — 1Department of Physics, University of Hamburg, D-20355 Hamburg, Germany — 2I. Institute for Theoretical Physics, University of Hamburg, D-20355 Hamburg, Germany — 3Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
Gapless materials in electronic contact with superconductors acquire proximity-induced superconductivity in a region near the interface. Here, we investigate the most miniature example of this so-called proximity effect on only a single quantum level of a surface state confined in a quantum corral on a superconducting substrate, built atom-by-atom using a scanning tunneling microscope. Whenever an eigenmode of the corral is pitched close to the Fermi energy by adjusting the corral's size, a pair of particle-hole symmetric states is found to enter the superconductor's gap. By comparison to a resonant level model of a spin-degenerate localized state coupled to a superconducting bath, we identify the in-gap states as scattering resonances theoretically predicted 50 years ago by K. Machida and F. Shibata, which had so far eluded detection. We further show that the observed anticrossings of the in-gap states indicate proximity-induced pairing in the quantum corral's eigenmodes. In a final step, we study how individual magnetic adatoms interact with the corral's eigenmodes.