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arXiv · 2301.01517

Tuning a two-impurity Kondo system by a moir\'e superstructure

Sergey Trishin·Christian Lotze·Friedemann Lohss·Giada Franceschi·Leonid I. Glazman·Felix von Oppen·Katharina J. Franke
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Abstract

Two-impurity Kondo models are paradigmatic for correlated spin-fermion systems. Working with Mn atoms on Au(111) covered by a monolayer of MoS$_2$, we tune the inter-adatom exchange via the adatom distance and the adatom-substrate exchange via the location relative to a moir\'e structure of the substrate. Differential-conductance measurements on isolated adatoms exhibit Kondo peaks with heights depending on the adatom location relative to the moir\'e structure. Mn dimers spaced by a few atomic lattice sites exhibit split Kondo resonances. In contrast, adatoms in closely spaced dimers couple antiferromagnetically, resulting in a molecular-singlet ground state. Exciting the singlet-triplet transition by tunneling electrons, we find that the singlet-triplet splitting is surprisingly sensitive to the moir\'e structure. We interpret our results theoretically by relating the variations in the singlet-triplet splitting to the heights of the Kondo peaks of single adatoms, finding evidence for coupling of the adatom spin to multiple conduction electron channels.

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Sergey Trishin, Christian Lotze, Friedemann Lohss, Giada Franceschi, Leonid I. Glazman, Felix von Oppen, Katharina J. Franke. 2023-01-04. Tuning a two-impurity Kondo system by a moir\'e superstructure. https://doi.org/10.1103/physrevlett.130.176201

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