Mixed-Valent Magnetism in CeFe2 from Multi-Impurity DFT+DMFT
Abstract
The microscopic origin of magnetism in CeFe2 has remained unresolved for almost forty years, where polarized-neutron diffraction and x-ray magnetic circular dichroism infer markedly different Ce 4f spin and orbital moments, that also are in disagreement with theory. We show here that within a relativistic multi-impurity DFT+DMFT framework, where the Fe 3d states are treated by spin-polarized T-matrix fluctuation exchange and Ce 4f orbitals by a bath-coupled configuration-interaction solver, this long standing problem is resolved. This level of theory is exclusive in reproducing magnetic moments (spin and orbital) for both the Ce and Fe atoms, yielding a total moment in agreement with the measured saturation moment. The theory put forth here is much closer to the atom specific moments reported from XMCD, compared to values from polarized-neutron diffraction. The occupation ⟨ nf⟩=0.85 and charge variance δnf2=0.27 establish substantial valence fluctuations, while the spectral function simultaneously recovers significant weight at the Fermi level together with separate incoherent structures. These results identify bath-mediated polarization and configuration mixing as the essential ingredients governing the electronic structure and magnetism of CeFe2.
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BibTeX
@misc{herzog2026mixedvalent,
title = {{Mixed-Valent Magnetism in CeFe$_2$ from Multi-Impurity DFT+DMFT}},
author = {Basile Herzog and Vladislav Borisov and Olle Eriksson},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.29241},
eprint = {2609.29241},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.29241},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Mixed-Valent Magnetism in CeFe_2 from Multi-Impurity DFT+DMFT
AU - Basile Herzog
AU - Vladislav Borisov
AU - Olle Eriksson
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.29241
UR - https://arxiv.org/abs/2609.29241
AB - The microscopic origin of magnetism in CeFe_2 has remained unresolved for almost forty years, where polarized-neutron diffraction and x-ray magnetic circular dichroism infer markedly different Ce 4f spin and orbital moments, that also are in disagreement with theory. We show here that within a relativistic multi-impurity DFT+DMFT framework, where the Fe 3d states are treated by spin-polarized T-matrix fluctuation exchange and Ce 4f orbitals by a bath-coupled configuration-interaction solver, this long standing problem is resolved. This level of theory is exclusive in reproducing magnetic moments (spin and orbital) for both the Ce and Fe atoms, yielding a total moment in agreement with the measured saturation moment. The theory put forth here is much closer to the atom specific moments reported from XMCD, compared to values from polarized-neutron diffraction. The occupation ⟨ n_f⟩=0.85 and charge variance δn_f^2=0.27 establish substantial valence fluctuations, while the spectral function simultaneously recovers significant weight at the Fermi level together with separate incoherent structures. These results identify bath-mediated polarization and configuration mixing as the essential ingredients governing the electronic structure and magnetism of CeFe_2.
ER -