title: Absence of a spin-signature from a single Ho adatom as probed by spin-sensitive tunneling.
abstract: Whether rare-earth materials can be used as single-atom magnetic memory is an ongoing debate in recent literature. Here we show, by inelastic and spin-resolved scanning tunnelling-based methods, that we observe a strong magnetic signal and excitation from Fe atoms adsorbed on Pt(111), but see no signatures of magnetic excitation or spin-based telegraph noise for Ho atoms. Moreover, we observe that the indirect exchange field produced by a single Ho atom is negligible, as sensed by nearby Fe atoms. We demonstrate, using ab initio methods, that this stems from a comparatively weak coupling of the Ho 4f electrons with both tunnelling electrons and substrate-derived itinerant electrons, making both magnetic coupling and detection very difficult when compared to 3d elements. We discuss these results in the context of ongoing disputes and clarify important controversies.
authors.affiliation: Department of Physics, Hamburg University, 20355 Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Steinbrecher
authors.affiliation: Department of Physics, Hamburg University, 20355 Hamburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Sonntag
authors.affiliation: Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, 52425 Jülich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: dos Santos Dias
authors.affiliation: Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, 52425 Jülich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Bouhassoune
authors.affiliation: Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, 52425 Jülich, Germany.
authors.forename: S
authors.identifier: http://orcid.org/0000-0003-2573-2841
authors.initials: S
authors.lastname: Lounis
authors.affiliation: Department of Physics, Hamburg University, 20355 Hamburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wiebe
authors.affiliation: Department of Physics, Hamburg University, 20355 Hamburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Wiesendanger
authors.affiliation: Department of Physics, Hamburg University, 20355 Hamburg, Germany.|Institute for Molecules and Materials (IMM), Radboud University, 6525 AJ Nijmegen, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Khajetoorians
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