Interfering Tunneling Paths through Magnetic Molecules on Superconductors: Asymmetries of Kondo and Yu-Shiba-Rusinov Resonances

Laëtitia Farinacci; Gelavizh Ahmadi; Michael Ruby; Gaël Reecht; Benjamin W. Heinrich; Constantin Czekelius; Felix von Oppen; Katharina J. Franke

doi:10.1103/PhysRevLett.125.256805

Interfering Tunneling Paths through Magnetic Molecules on Superconductors: Asymmetries of Kondo and Yu-Shiba-Rusinov Resonances

Laëtitia Farinacci, Gelavizh Ahmadi, Michael Ruby, Gaël Reecht, Benjamin W. Heinrich, Constantin Czekelius, Felix von Oppen, Katharina J. Franke

DOI 10.1103/PhysRevLett.125.256805 · Physical Review Letters

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Abstract

Magnetic adsorbates on superconductors induce a Kondo resonance outside and Yu-Shiba-Rusinov (YSR) bound states inside the superconducting energy gap. When probed by scanning tunneling spectroscopy, the associated differential-conductance spectra frequently exhibit characteristic bias-voltage asymmetries. Here, we observe correlated variations of Kondo and YSR asymmetries across an Fe-porphyrin molecule adsorbed on Pb(111). We show that both asymmetries originate in interfering tunneling paths via a spin-carrying orbital and the highest occupied molecular orbital (HOMO). Strong evidence for this model comes from nodal planes of the HOMO, where tunneling reveals symmetric Kondo and YSR resonances. Our results establish an important mechanism for the asymmetries of Kondo and YSR line shapes.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Pb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown