Variable Charge State, Magnetic Excitations, and Kondo Effect of Sm/g/Ir(111)

Abstract

Using low-temperature scanning tunneling microscopy we investigate the charge state, magnetic excitations, and Kondo features of individual Sm adatoms on graphene/Ir(111). Depending on the number and distance of their neighbors, Sm atoms can be in two discrete charge states. At certain distances, a reversible transition between these two states is induced by the electric field of the STM tip leading to concentric charge rings in the images. Only atoms in one of the two charge states exhibit magnetic excitations in dI/dV spectra. Two such excitations are located at 35~meV and 54~meV and related to transitions from the J = 1/2 ground state doublet to the first crystal field split J = 3/2 multiplet. Together with the intra-atomic exchange excitations at higher energy, these observations indicate that Sm transfers one 6s electron to the substrate while it retains its gas-phase 4f filling. New for lanthanide adatoms, we observe a Kondo resonance. The Zeeman splitting of the Kondo peak reveals that Sm retains its large gas-phase g-factor. Comparison of dI/dV spectra to cotunneling theory yields the crystal field acting on the 4f shell and, consequently, on the J = 3/2 quadruplet, confirms Sm⁺ as the ground state, and identifies Sm²⁺ as being energetically close, thereby rationalizing our observation of variable charge states.

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BibTeX RIS

BibTeX

@misc{shan2026variable,
  title = {{Variable Charge State, Magnetic Excitations, and Kondo Effect of Sm/g/Ir(111)}},
  author = {Shixuan Shan and Tamara de Ara and Lina Liu and Zhipeng Wang and Marina Pivetta and François Patthey and Tadahiro Komeda and Daria Kývala and Jindřich Kolorenč and Harald Brune},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.05394},
  eprint = {2609.05394},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.05394},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Variable Charge State, Magnetic Excitations, and Kondo Effect of Sm/g/Ir(111)
AU  - Shixuan Shan
AU  - Tamara de Ara
AU  - Lina Liu
AU  - Zhipeng Wang
AU  - Marina Pivetta
AU  - François Patthey
AU  - Tadahiro Komeda
AU  - Daria Kývala
AU  - Jindřich Kolorenč
AU  - Harald Brune
PY  - 2026
DA  - 2026/09/04
PB  - arXiv
DO  - 10.48550/arxiv.2609.05394
UR  - https://arxiv.org/abs/2609.05394
AB  - Using low-temperature scanning tunneling microscopy we investigate the charge state, magnetic excitations, and Kondo features of individual Sm adatoms on graphene/Ir(111). Depending on the number and distance of their neighbors, Sm atoms can be in two discrete charge states. At certain distances, a reversible transition between these two states is induced by the electric field of the STM tip leading to concentric charge rings in the images. Only atoms in one of the two charge states exhibit magnetic excitations in dI/dV spectra. Two such excitations are located at 35~meV and 54~meV and related to transitions from the J = 1/2 ground state doublet to the first crystal field split J = 3/2 multiplet. Together with the intra-atomic exchange excitations at higher energy, these observations indicate that Sm transfers one 6s electron to the substrate while it retains its gas-phase 4f filling. New for lanthanide adatoms, we observe a Kondo resonance. The Zeeman splitting of the Kondo peak reveals that Sm retains its large gas-phase g-factor. Comparison of dI/dV spectra to cotunneling theory yields the crystal field acting on the 4f shell and, consequently, on the J = 3/2 quadruplet, confirms Sm^+ as the ground state, and identifies Sm^2+ as being energetically close, thereby rationalizing our observation of variable charge states.
ER  -

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