Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 15: Focus Session Many-Body Phenomena in Nanomagnets: Kondo, Spinons, Spinarons and Beyond (joint session O/TT)

O 15.5: Invited Talk

Monday, March 17, 2025, 17:00–17:30, H24

Spinarons: A new view on emerging spin-driven many-body phenomena in nanostructures — •Samir Lounis — Peter Grünberg Institut, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany — Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany — Institute of Physics, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany

Many-body phenomena are crucial in physics, particularly in condensed matter, influencing electronic, magnetic, thermodynamic, and transport properties. They leave distinct spectroscopic signatures, such as Kondo, excitonic, and polaronic features, arising from specific 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.
[1] V. Madhavan et al., Science 280, 567 (1998); [2] J. Bouaziz et al., Nat. Commun. 11, 6112 (2020); [3] F. Friedrich et al., Nat. Phys. 20, 28 (2024); [4] N. Noei et al., Nanoletters 23, 8988 (2023)

Keywords: Spinaron; Many-body phenomena; Theory of scanning tunnelling spectroscopy; Magnetic adatoms; Spin-orbit interaction