Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 6: Focus Session Many-Body Phenomena in Nanomagnets: Kondo, Spinons, Spinarons and Beyond (joint session O/TT)

TT 6.4: Invited Talk

Monday, March 17, 2025, 16:30–17:00, H24

Evidence for spinarons in Co atoms on noble metal (111) surfaces — •Artem Odobesko — Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg

The zero-bias anomaly in the tunnelling differential conductance of Co atoms on Au(111) [1], long attributed to the Kondo effect, has recently been reinterpreted [2] as evidence of the spinaron -- a novel many-body excitation arising from the interplay between spin excitations and conduction electrons. In our study, we used spin-polarized scanning tunneling spectroscopy (STS) on Co atoms on Cu(111) and Au(111) under high magnetic fields, revealing field-induced energy shifts and spin-resolved spectral features that challenge the conventional Kondo interpretation. Instead, our findings provide the first experimental confirmation of the spinaron [3].

We also investigated the role of hybridization with the substrate in spinaron formation, focusing on the reconstructed Au(111) surface. The unique local electronic environments created by the herringbone reconstruction strongly influence the hybridization strength and spectral features of Co adatoms, revealing a clear link between adsorption site, hybridization, and spinaronic excitations. Our results shed light on the fundamental mechanisms driving spinaron formation.

[1] V. Madhavan, et al., Science 280, 567 (1998)

[2] J. Bouaziz, et al., Nat. Comm. 11, 6112 (2020)

[3] F. Friedrich, et al., Nat. Phys. (2023)

Keywords: Kondo effect, Spinaron, Spin Excitation