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PreprintCC BY 4.0arXiv

Direct imaging of the Ni eg hole orbitals in the bilayer nickelate La2SmNi2O7

  • Ethan Saïman
  • Feiyu Li
  • Junjie Zhang
  • Jean-Pascal Rueff
  • Victor Balédent
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Abstract

Models of unconventional superconductivity in cuprates and nickelates depend sensitively on the distribution of valence electrons among the d orbitals. But accurately determining the orbital electron or hole occupations in these systems remains a difficult and unresolved task. Here, using s-core-level non-resonant inelastic x-ray scattering at the Ni M1 edge, we determine the angular distribution of the Ni 3d holes in a single crystal of La2SmNi2O7. Our results demonstrate that the hole occupation ratio hz/hx = 0.94±0.06, thus significantly above the expected value of 2/3 for a filled dz2 orbitals models and close to value expected in a Hund's-coupling picture. Our results support superconductivity scenarios in which both eg orbitals contribute to the electron-pairing mechanism in La2SmNi2O7.

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Cite

BibTeXRIS
BibTeX
@misc{saiman2026direct,
  title = {{Direct imaging of the Ni $e_g$ hole orbitals in the bilayer nickelate La$_2$SmNi$_2$O$_7$}},
  author = {Ethan Saïman and Feiyu Li and Junjie Zhang and Jean-Pascal Rueff and Victor Balédent},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.01118},
  eprint = {2611.01118},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.01118},
  note = {CC BY 4.0},
}
RIS
TY  - UNPB
TI  - Direct imaging of the Ni e_g hole orbitals in the bilayer nickelate La_2SmNi_2O_7
AU  - Ethan Saïman
AU  - Feiyu Li
AU  - Junjie Zhang
AU  - Jean-Pascal Rueff
AU  - Victor Balédent
PY  - 2026
DA  - 2026/11/01
PB  - arXiv
DO  - 10.48550/arxiv.2611.01118
UR  - https://arxiv.org/abs/2611.01118
AB  - Models of unconventional superconductivity in cuprates and nickelates depend sensitively on the distribution of valence electrons among the d orbitals. But accurately determining the orbital electron or hole occupations in these systems remains a difficult and unresolved task. Here, using s-core-level non-resonant inelastic x-ray scattering at the Ni M_1 edge, we determine the angular distribution of the Ni 3d holes in a single crystal of La_2SmNi_2O_7. Our results demonstrate that the hole occupation ratio hz/hx = 0.94±0.06, thus significantly above the expected value of 2/3 for a filled d_z^2 orbitals models and close to value expected in a Hund's-coupling picture. Our results support superconductivity scenarios in which both e_g orbitals contribute to the electron-pairing mechanism in La_2SmNi_2O_7.
ER  -