Spinarons: A new view on emerging spin-driven many-body phenomena in nanostructures

Many-body phenomena are paramount in physics. In condensed matter, their hallmark is considerable on a wide range of material characteristics spanning electronic, magnetic, thermodynamic and transport properties. They potentially imprint non-trivial signatures in spectroscopic measurements, such as those assigned to Kondo, excitonic and polaronic features, whose emergence depends on the involved degrees of freedom. Since more than two decades Cobalt atoms on the (111) surfaces of noble metals have been a paradigm for the Kondo effect in scanning tunnelling spectroscopy experiments [1]. However, our recent first-principles predictions [2] followed by STS experiments in high magnetic fields [3,4] challenge this notion. Our findings reveal that the observed transport anomalies stem from spin excitations of Co atoms, forming a new many-body state—the spinaron—distinct from the Kondo resonance. I will delve into the spinaron origins, their unique properties, and implications explored through the recent atomic manipulation experiments. This work opens pathways to investigate and engineer these hybrid states in nanostructures, offering new insights into fundamental many-body states.
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[2] J. Bouaziz, F. Guimarães, S. Lounis, Nat. Commun. 11, 6112 (2020)
[3] F. Friedrich, A. Odobesko, J. Bouaziz, S. Lounis, M. Bode, Nat. Phys. 20, 28 (2024)
[4] N. Noei, R. Mozara, A. Montero, S. Brinker, N. Ide, F. Guimarães, A. Lichtenstein, R. Berndt, S. Lounis, A. Weismann, Nanoletters 23, 8988 (2023)