Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 52: Focus Session: Spins on Surfaces studied by Atomic Scale Spectroscopies V

O 52.2: Vortrag

Mittwoch, 20. März 2024, 15:30–15:45, MA 004

Evidence for spinarons in Co atoms on noble metal (111) surfaces — •Artem Odobesko, Felix Friedrich, and Matthias Bode — Julius-Maximilians-Universität Würzburg, Physikalisches Institut, Experimentelle Physik II, Am Hubland, 97074 Würzburg, Germany

The first Kondo effect’s detection on individual Co atoms on Au(111) surface [1] was associated with a zero-bias anomaly (ZBA) in the differential conductance signal, explained by Fano resonance due to interfering tunneling paths into the Kondo state and atomic orbitals. Recent calculations [2] challenge this interpretation, suggesting that the ZBA is a mix of Co atom spin excitations and the spinaron, a magnetic polaron resulting from the interaction of spin excitations with conduction electrons. Our study used spin-polarised STS on Co atoms on Cu and Au (111) surfaces in magnetic fields up to 12 T. Our comprehensive study of the responses of the ZBA on Co atoms on Cu(111) to an external magnetic field, in conjunction with spin-polarized measurements, allowed us to discriminate between various theoretical models. We observe a field-induced energy shift and experimentally determine the spin character of the spectral features, exhibiting a behavior contrary to Kondo expectations but in line with the spinaron. Consequently, we invalidate the prevailing Kondo-based interpretation of the ZBA in favor of the spinaron and, for the first time experimentally, detect this novel many-body excitation [3].
[1] V. Madhavan et al., Science 280, 567 (1998)
[2] J. Bouazizet al., Nat. Comm. 11, 6112 (2020)
[3] F. Friedrich, et al., Nat. Phys. (2023)

Keywords: Kondo effect; Spin Excitations; Spinaron; SP-STM