Pair excitations of a quantum spin on a proximitized superconductor

Abstract

A magnetic impurity interacting with a superconductor develops a rich excitation spectrum formed by superposition of quasiparticles and spin states, which appear as Yu-Shiba-Rusinov and spin-flip excitations in tunneling spectra. Here, we show that tunneling electrons can also excite a superconducting pair-breaking transition in the presence of magnetic impurities, which is hidden for electrons on bare superconductors. Combining scanning tunneling spectroscopy with theoretical modeling, we map the excitation spectrum of a Fe-porphyrin molecule on the Au/V(100) proximitized surface into a manifold of many-body excitations and follow their behavior across a parity-changing transition. Pair excitations emerge in the tunneling spectra as peaks outside the gap in the strong interaction regime, scaling with the pair correlation. Our results unravel the quantum nature of magnetic impurities on superconductors and prove that pair excitations are parity detectors for magnetic impurities.

14 pages, 11 figures

References in corpus (10)

• Protection of excited spin states by a superconducting energy gap
• Properties of anisotropic magnetic impurities on surfaces
• Magnetic anisotropy effects on quantum impurities in superconducting host
• Proximity-induced Shiba states in a molecular junction
• Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions
• Quantum Yu-Shiba-Rusinov dimers
• Resonance-enhanced vibrational spectroscopy of molecules on a superconductor
• Extending the spin excitation lifetime of a magnetic molecule on a proximitized superconductor
• Theory of spin inelastic tunneling spectroscopy for superconductor-superconductor and superconductor-metal junctions
• Spin Inelastic Electron Tunneling Spectroscopy on Local Magnetic Moment Embedded in Josephson Junction

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• Theory of a Single Magnetic Impurity on a Thin Metal Film in Proximity to a Superconductor
• Quantum spin driven Yu-Shiba-Rusinov multiplets and fermion-parity-preserving phase transition in K${}_3$C${}_{60}$
• Robust Spin Polarization of Yu-Shiba-Rusinov States in Superconductor/Ferromagnetic Insulator Heterostructures
• Diluted Yu-Shiba-Rusinov arrays on the $\beta$-Bi${}_2$Pd anisotropic superconductor
• Quantifying the quantum nature of high spin YSR excitations in transverse magnetic field
• Probing Magnetic and Triplet Correlations in Spin-Split Superconductors with Magnetic Impurities
• Shaping graphene superconductivity with nanometer precision
• A Large-$N$ Approach to Magnetic Impurities in Superconductors
• A minimal model of inelastic tunneling of vibrating magnetic molecules on superconducting substrates
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