Katharina Franke

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Magnetic impurities in conventional superconductors induce a pair-breaking potential, which leads
to bound states inside the superconducting energy gap. These states are called Yu-Shiba-Rusinov
states, or short: Shiba states, and can be probed by scanning tunneling spectroscopy at the atomic
scale.
Here, we explore the Shiba states of individual magnetic atoms on superconducting substrates. The
patterns of Shiba states of individual Mn atoms on a Pb(100) surface exhibit the shape of the
corresponding spin-carrying d-orbital [1]. When the adatoms are brought into sufficiently close
distance, they hybridize by forming symmetric and anti-symmetric linear combinations of the Shiba
wave functions [2].
NbSe2 is a van der Waals-layered material with quasi-2D character. In addition to its superconducting
properties it hosts a charge-density wave (CDW) at low temperatures. Magnetic atoms and
molecules have been shown to give rise to long-range oscillatory Shiba states [3,4]. Here, we show
that the CDW affects the energy and symmetry patterns of Shiba states around individual Fe atoms.
[1] M. Ruby, Y. Peng, F. von Oppen, B.W. Heinrich, K.J. Franke, Phys. Rev. Lett. 117, 186801 (2016)
[2] M. Ruby, B.W. Heinrich, Y. Peng, F. von Oppen, K.J. Franke, Phys. Rev. Lett. 120, 156803 (2018)
[3] G. Menard, et al, Nat. Phys. 11, 1013 (2015)
[4] S. Kezilebieke, M. Dvorak, T. Ojanen, P. Liljeroth, Nano Lett. 18, 2311 (2018)

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Freie Universität Berlin
Seminar Room of the Institute of Physics II
Contact: Yoichi Ando