Long range and highly tunable interaction between local spins coupled to a superconducting condensate

Küster, Felix; Brinker, Sascha; Lounis, Samir; Parkin, S. S. P.; Sessi, Paolo

doi:10.1038/s41467-021-26802-x

Cited by 37 publications

(32 citation statements)

References 60 publications

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“…1A . This allows us to analyze the effect of local magnetic moments coupled to an electron bath, while excluding the influence of nearby adatoms, which can couple to each other by indirect interactions mediated by the conduction electrons, i.e., the RKKY coupling, ultimately influencing the magnetic adatom ground state ( 48 ).…”

Section: Resultsmentioning

confidence: 99%

Anomalous excitations of atomically crafted quantum magnets

et al. 2022

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High–energy resolution spectroscopic studies of quantum magnets proved extremely valuable in accessing magnetodynamics quantities, such as energy barriers, magnetic interactions, and lifetime of excited states. Here, we investigate a previously unexplored flavor of low-energy spin excitations for quantum spins coupled to an electron bath. In sharp contrast to the usual tunneling signature of two steps symmetrically centered around the Fermi level, we find a single step in the conductance. Combining time-dependent and many-body perturbation theories, magnetic field–dependent tunneling spectra are explained as the result of an interplay between weak magnetic anisotropy energy, magnetic interactions, and Stoner-like electron-hole excitations that are strongly dependent on the magnetic states of the nanostructures. The results are rationalized in terms of a noncollinear magnetic ground state and the dominance of ferro- and antiferromagnetic interactions. The atomically crafted nanomagnets offer an appealing model for the exploration of electrically pumped spin systems.

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Section: Resultsmentioning

confidence: 99%

Anomalous excitations of atomically crafted quantum magnets

et al. 2022

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“…Details on sample preparation and measurement protocols can be found in Methods. We focus on Cr atoms indirectly coupled through the (110) surface of niobium, a system which has recently been demonstrated to allow for the tuning of interactions by actively using the superconducting condensate to mediate indirect coupling among the localized Cr spins 28 . By contrast with atomic chains created by self-assembly, the use of direct atomic manipulation allows for much greater flexibility since it makes it possible to vary several key experimental parameters such as: (i) chain length, (ii) crystallographic direction, and (iii) distance between local magnetic moments.…”

Section: Resultsmentioning

confidence: 99%

“…Here, we use atomic manipulation techniques to create dilute spin chains, where Shiba bands are generated by indirect coupling mediated by the superconducting condensate 27,28 . We demonstrate that the presence of YSR pairs very close to the center of the superconducting gap allows one to cross the quantum phase transition, a necessary but not sufficient condition for the creation of topologically non-trivial superconducting phases [1][2][3] , for relatively short chains.…”

Section: Introductionmentioning

confidence: 99%

Non-Majorana modes in diluted spin chains proximitized to a superconductor

Küster,

Brinker,

Hess

et al. 2021

Preprint

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Spin chains proximitized with superconducting condensates have emerged as one of the most promising platforms for the realization of Majorana modes [1][2][3][4][5][6] . The recent use of atomic manipulation techniques raised great expectations for successfully creating and controlling such chains [7][8][9][10] . Here, we craft diluted spin chains atom-by-atom following seminal theoretical proposal suggesting indirect coupling mechanisms as a viable route to trigger topological superconductivity 3 . We demonstrate that, starting from deep Shiba states, it is possible to cross the quantum phase transition, a necessary condition for the emergence of topological superconductivity, for very short chains. This transition is associated with the emergence of highly localized zero energy end modes. The use of a substrate with highly anisotropic Fermi surface enables to create spin chains characterized by distinct magnetic configurations along

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“…This allows us to analyze the effect of local magnetic moments coupled to an electron bath, while excluding the influence of nearby adatoms which can couple to each other by indirect interactions mediated by the conduction electrons, i.e. the RKKY coupling, ultimately influencing the magnetic adatom ground state 48 .…”

Section: Resultsmentioning

confidence: 99%

Anomalous excitations of atomically crafted quantum magnets

Brinker,

Küster,

Parkin

et al. 2021

Preprint

Self Cite

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High energy resolution spectroscopic studies of quantum magnets have proven to be extremely valuable in directly accessing magnetodynamics quantities, such as energy barriers, magnetic interactions, lifetime of excited states and fluctuations at the most fundamental level. Here, we explore the existence of a new flavor of low-energy spin-excitations for quantum spins coupled to an electron bath. In sharp contrast to the usual tunneling signature of two steps symmetrically centered around the Fermi level, we find a single step in the conductance. Combining time-dependent and many-body perturbation theories, magnetic field-dependent tunneling spectra are explained to be the result of an interplay between weak magnetic anisotropy energy, magnetic interactions and Stoner-like electron-hole excitations that are strongly dependent on the magnetic states of the studied nanostructures. We additionally map the evolution of the conductance peak in artificial nanostructures crafted atom-by-atom, which show clear evidence of spin-coupled behavior. The results are rational-1

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Long range and highly tunable interaction between local spins coupled to a superconducting condensate

Cited by 37 publications

References 60 publications

Anomalous excitations of atomically crafted quantum magnets

Anomalous excitations of atomically crafted quantum magnets

Non-Majorana modes in diluted spin chains proximitized to a superconductor

Anomalous excitations of atomically crafted quantum magnets

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