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

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

doi:10.1103/physrevlett.125.256805

Cited by 35 publications

(23 citation statements)

References 47 publications

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“…They inherited their name from the subgap states in an analogous system, namely magnetic adatoms on a superconducting surface, which are widely studied by scanning tunneling microscope experiments. [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83] We will call the transport mechanism responsible for the non-local signal in Ref. 36 Shibaassisted local pair tunneling (SPT), since it is enabled by the Shiba state, and it involves subsequent transitions of two electrons (elements of a Cooper pair) into the same normal lead.…”

Section: Introductionmentioning

confidence: 99%

From Cooper pair splitting to the non-local spectroscopy of a Shiba state

Scherübl,

Fülöp,

Gramich

et al. 2021

Preprint

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Cooper pair splitting (CPS) is a way to create spatially separated, entangled electron pairs. To this day, CPS is often identified in experiments as a spatial current correlation. However, such correlations can arise even in the absence of CPS, when a quantum dot is strongly coupled to the superconductor, and a subgap Shiba state is formed. Here, we present a detailed experimental characterization of those spatial current correlations, as the tunnel barrier strength between the quantum dot and the neighboring normal electrode is tuned. The correlation of the non-local signal and the barrier strength reveals a competition between CPS and the non-local probing of the Shiba state. We describe our experiment with a simple transport model, and obtain the tunnel couplings of our device by fitting the model's prediction to the measured conductance correlation curve. Furthermore, we use our theory to extract the contribution of CPS to the non-local signal.

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Section: Introductionmentioning

confidence: 99%

From Cooper pair splitting to the non-local spectroscopy of a Shiba state

Scherübl,

Fülöp,

Gramich

et al. 2021

Preprint

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“…The formation of a phase coherent ground state of many Cooper pairs results in resistance vanishing when the temperature is lowered to below 29 . When magnetic impurities are incorporated into the system, the interplay between these two competing ground states has been a subject of great interest 1 , 30 – 35 . In superconducting alloys, Kondo effect can change its superconducting properties greatly 36 – 38 .…”

Section: Introductionmentioning

confidence: 99%

“…The competition between superconductivity and Kondo effect has been of great interests 39 – 42 . In recent years, the Kondo effect has also been studied in many new superconductors materials 31 – 35 , in 2D topological superconductors and 3D topological insulators 43 , 44 . Similar resisivity minimum was also observed in high- superconductors 45 .…”

Section: Introductionmentioning

confidence: 99%

Kondo effect and superconductivity in niobium with iron impurities

Zeng

Zhou

Liang

et al. 2021

Sci Rep

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Kondo effect is an interesting phenomenon in quantum many-body physics. Niobium (Nb) is a conventional superconductor important for many superconducting device applications. It was long thought that the Kondo effect cannot be observed in Nb because the magnetic moment of a magnetic impurity, e.g. iron (Fe), would have been quenched in Nb. Here we report an observation of the Kondo effect in a Nb thin film structure. We found that by co-annealing Nb films with Fe in Argon gas at above 400 $$^{\circ }$$ ∘ C for an hour, one can induce a Kondo effect in Nb. The Kondo effect is more pronounced at higher annealing temperature. The temperature dependence of the resistance suggests existence of remnant superconductivity at low temperatures even though the system never becomes superconducting. We find that the Hamann theory for the Kondo resistivity gives a satisfactory fitting to the result. The Hamann analysis gives a Kondo temperature for this Nb–Fe system at $$\sim $$ ∼ 16 K, well above the superconducting transition onset temperature 9 K of the starting Nb film, suggesting that the screening of the impurity spins is effective to allow Cooper pairs to form at low temperatures. We suggest that the mechanism by which the Fe impurities retain partially their magnetic moment is that they are located at the grain boundaries, not fully dissolved into the bcc lattice of Nb.

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“…The total tunneling amplitude emerges from interference between these cotunneling paths. As a function of tip location, their relative contributions vary in accordance with the orbital wave functions, explaining the spatial variations in the potential scattering strength U [32].…”

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confidence: 98%

“…S4a). The variation in U can be understood as an interference effect originating from parallel tunneling paths [28][29][30], similar to tunneling through metal-organic complexes [31,32]. To gain insight into the tunneling paths, we record dI/dV spectra for a larger bias-voltage range (Fig.…”

mentioning

confidence: 99%

Moiré tuning of spin excitations: Individual Fe atoms on MoS$_2$/Au(111)

Trishin,

Lotze,

Bogdanoff

et al. 2021

Preprint

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

Cited by 35 publications

References 47 publications

From Cooper pair splitting to the non-local spectroscopy of a Shiba state

From Cooper pair splitting to the non-local spectroscopy of a Shiba state

Kondo effect and superconductivity in niobium with iron impurities

Moiré tuning of spin excitations: Individual Fe atoms on MoS$_2$/Au(111)

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