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PreprintarXiv licencearXiv

Orbital-selective correlations in kagome flat bands of Co3Sn2S2

  • Rongxiang Zhu
  • Huaiqiang Wang
  • Haijun Zhang
  • Jianzhou Zhao
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Abstract

Geometrical flat bands provide an ideal platform for studying electronic correlations and quantum-geometric effects. Although the ferromagnetic Weyl semimetal \CoSnS is generally considered a moderately correlated system, recent spectroscopy experiments have revealed a flat-band feature near the Fermi level (EF) that is absent in conventional density functional theory (DFT) calculations. Using DFT plus dynamical mean-field theory and a minimal kagome model, we show that this feature arises not from heavy-fermion-like dynamical band renormalization, but from the shifting of a dx2−y2 dominated geometrical kagome flat band toward EF driven by orbital- and spin-dependent self-energies. The relocated flat band enhances the local Berry curvature near EF, resulting in a strongly energy-dependent anomalous Hall conductivity and a giant anomalous Nernst effect. Our findings establish an orbital-selective correlation mechanism for positioning geometrical flat bands at EF, and propose anomalous thermoelectric transport as a sensitive probe of flat band induced topology.

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Cite

BibTeXRIS
BibTeX
@misc{zhu2026orbitalselective,
  title = {{Orbital-selective correlations in kagome flat bands of Co$_3$Sn$_2$S$_2$}},
  author = {Rongxiang Zhu and Huaiqiang Wang and Haijun Zhang and Jianzhou Zhao},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.35255},
  eprint = {2610.35255},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.35255},
}
RIS
TY  - UNPB
TI  - Orbital-selective correlations in kagome flat bands of Co_3Sn_2S_2
AU  - Rongxiang Zhu
AU  - Huaiqiang Wang
AU  - Haijun Zhang
AU  - Jianzhou Zhao
PY  - 2026
DA  - 2026/10/26
PB  - arXiv
DO  - 10.48550/arxiv.2610.35255
UR  - https://arxiv.org/abs/2610.35255
AB  - Geometrical flat bands provide an ideal platform for studying electronic correlations and quantum-geometric effects. Although the ferromagnetic Weyl semimetal \CoSnS is generally considered a moderately correlated system, recent spectroscopy experiments have revealed a flat-band feature near the Fermi level (EF) that is absent in conventional density functional theory (DFT) calculations. Using DFT plus dynamical mean-field theory and a minimal kagome model, we show that this feature arises not from heavy-fermion-like dynamical band renormalization, but from the shifting of a d_x^2−y^2 dominated geometrical kagome flat band toward EF driven by orbital- and spin-dependent self-energies. The relocated flat band enhances the local Berry curvature near EF, resulting in a strongly energy-dependent anomalous Hall conductivity and a giant anomalous Nernst effect. Our findings establish an orbital-selective correlation mechanism for positioning geometrical flat bands at EF, and propose anomalous thermoelectric transport as a sensitive probe of flat band induced topology.
ER  -