SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 33: Spins on Surfaces at the Atomic Scale III

O 33.6: Vortrag

Dienstag, 28. März 2023, 12:00–12:15, REC C 213

Are excitations of the 4f magnetic moment visible to the scanning tunneling spectroscopy? — Daria Kyvala and •Jindrich Kolorenc — Institute of Physics (FZU), Czech Academy of Sciences, Praha, Czech Republic

The inelastic electron tunneling spectroscopy (IETS) has repeatedly proved useful for investigation of spin excitations in transition-metal atoms on surfaces [1,2]. Analogous observations of magnetic excitations in rare-earth atoms remained elusive, the reasoning behind it being that the 4f states that carry the magnetic moment are compact, buried in the atomic core, and the tunneling through a rare-earth atom proceeds via outer, more diffuse orbitals like 5d or 6s. Recently, the exchange coupling between the spin in these outer orbitals and the 4f magnetic moment was observed in IETS as an excitation in the 50–200 meV range [3]. In the same time, some excitations at lower energies were also seen. Employing a variant of the cotunneling theory [4,5] we demonstrate these excitations to be the elusive crystal-field excitations of the 4f magnetic moment. The selection rules prevent the IETS from detecting enough transitions to fully determine the crystal field by itself, but the visible transitions can be used in conjunction with the x-ray absorption spectra [6] to refine the existing estimates of the crystal field. — [1] A. J. Heinrich at al., Science 306, 466 (2004); [2] C. F. Hirjibehedin at al., Science 317, 1199 (2007); [3] M. Pivetta at al., PRX 10, 031054 (2020); [4] F. Delgado and J. Fernández-Rossier, PRB 84, 045439 (2011); [5] C. Wäckerlin et al., ACS Nano 16, 16402 (2022); [6] R. Baltic et al., PRB 98, 024412 (2018).