Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: Superconductivity: Tunnelling and Josephson Junctions
TT 26.8: Vortrag
Donnerstag, 8. September 2022, 11:30–11:45, H10
Nonreciprocity in current-biased Josephson junctions in the presence of Yu-Shiba-Rusinov bound states — •Martina Trahms1, Bharti Mahendru1, Idan Tamir1, Larissa Melischek1, Jacob F. Steiner1, Nils Bogdanoff1, Olof Peters1, Gaël Reecht1, Clemes B. Winkelmann2, Felix von Oppen1, and Katharina J. Franke1 — 1Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany — 2Univ. Grenoble Alpes, Institute Néel, 38042 Grenoble, France
Magnetic impurities on superconducting surfaces are known to locally disturb Cooper pairs and form Yu-Shiba-Rusinov (YSR) states. We employ current-biased Josephson spectroscopy in a scanning tunnelling microscope to study the phase dynamics of Josephson junctions in the presence of YSR states. For that purpose Mn and Cr adatoms are evaporated on a superconducting Pb(111) surface and investigated with a superconducting Pb tip. We observe switching currents that are significantly larger than the retrapping currents, identifying the junction as underdamped. In the presence of magnetic atoms, a local reduction of switching currents is observed. Additionally, we find a nonreciprocal behavior of the retrapping currents with respect to the current-sweep direction, i.e., the absolute value of the retrapping current depends on whether the current sweep starts at positive or negative bias values. In our experiment both species of magnetic atoms lead to a nonreciprocal retrapping-current behavior, albeit with a different directionality. We suggest a correlation between the damping of the Josephson junction and the electron-hole asymmetry of the YSR states.