Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 3: Focus Session: Spins on Surfaces studied by Atomic Scale Spectroscopies I
O 3.2: Talk
Monday, March 18, 2024, 11:00–11:15, MA 004
Magnetic field dependence of Yu-Shiba-Rusinov (YSR) excitations — •Niels P.E. van Mullekom1, Benjamin Verlhac1, Werner M.J. van Weerdenburg1, Hermann Osterhage1, Manuel Steinbrecher1, Katharina J. Franke2, and Alexander A. Khajetoorians1 — 1Institute for Molecules and Materials, Radboud University Nijmegen, the Netherlands — 2Fachbereich Physik, Freie Universität Berlin, Germany.
Yu-Shiba-Rusinov (YSR) states arise from the exchange coupling between a local spin and a superconductor and can be characterized by resonances inside the gap superconducting gap. From the in-gap excitations alone, the interplay of this exchange interaction with other energy scales, as well as the role of higher spin degrees of freedom is not clear. Magnetic field dependent characterization could clarify this, but most studies of YSR states to date have been limited to bulk superconductors, which easily quench in the presence of modest magnetic fields.
Utilizing the enhanced critical fields of a thin superconducting film we characterize the magnetic phase diagram of a molecule on the surface using high resolution milliKelvin scanning tunneling microscopy and spectroscopy. We observe nontrivial changes in the YSR excitations, that go beyond the trends that are expected in a spin 1/2 picture. We relate these changes to the various properties of the molecule, such as the role of multiple channels and magnetic anisotropy. These results provide an in-depth and detailed approach to understand the role of high spin states in the YSR excitations.
Keywords: Yu-Shiba-Rusinov (YSR); Magnetic field; Thin Film Superconductor (SC); Scanning Tunneling Microscopy/Spectroscopy; Spin