Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 84: Focus Session: Spins on Surfaces II (joint session O/MA)
O 84.7: Vortrag
Donnerstag, 4. April 2019, 16:45–17:00, H15
Investigation of the effect of Mn adatoms on the critical current in a STM Josephson junction — •Nils Bogdanoff1, Rika Simon1, Olof Peters1, Gaël Reecht1, Clemens B. Winkelmann2, and Katharina J. Franke1 — 1Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Univ. Grenoble Alpes, Inistitut Neél, 25 Avenue des Martyrs, 38042 Grenoble, France
Atomic spins on superconducting surfaces introduce so called Yu-Shiba-Rusinov (YSR) states inside the superconducting gap as fingerprint of a magnetic interaction. Furthermore, theory predicts a renormalization of the local order parameter. Differential conductance spectroscopy reveals the YSR states but not the intrinsic order of the superconducting groundstate. Using a Josephson junction the order parameter can be determined directly by measuring its characteristic critical current.
We use a Pb tip in a scanning tunneling microscope (STM) and a Pb substrate as a SIS junction. The precise control over the STM tip enables high real-space resolution to study for example defects on atomic length scales.
As was shown before [1], a reduction of the critical current can be observed on iron adatoms on a Pb(110) surface.
Here, we measure the critical current caused by Mn adatoms on Pb(111) in voltage- and current-biased Josephson junctions. We show that these more strongly reduce the critical current than the Fe adatoms.
[1] M. T. Randeria et al., Scanning Josephson spectroscopy on the atomic scale, Phys. Rev. B 93, 161115(R), 2016