Dynamical Valence Fluctuations and Magnetic Anisotropy in Sm(Co,Cu)5
Abstract
The magnetic properties of Sm-based intermetallics are governed by a delicate interplay between localized 4f states, exchange interactions, and valence fluctuations, yet the role of dynamical 4f correlations remains poorly understood. Here we investigate the electronic structure and magnetic anisotropy of SmCo5 and SmCu5 using self-consistent DFT+U(ED), which explicitly treats dynamical fluctuations of the Sm 4f shell. We find that SmCo5 exhibits pronounced Sm2+--Sm3+ valence fluctuations, with the 4f ground state dominated by f5 and f6 configurations. The resulting dynamical 4f correlations yield near compensation of the Sm spin and orbital moments and provide a quantitative description of the electronic structure, magnetic moments, and large uniaxial magnetic anisotropy of SmCo5. Upon replacing Co with Cu, the balance shifts toward the f6 configuration, with substantial changes in the Sm spin and orbital moments. In SmCu5, this evolution of the 4f configuration is accompanied by a pronounced reduction of both the total magnetic moment and magnetic anisotropy. These results demonstrate that dynamical 4f valence fluctuations are essential for understanding the contrasting magnetic properties of SmCo5 and SmCu5 and provide a microscopic framework for describing magnetic anisotropy upon Co to Cu substitution in Sm(Co,Cu)5.
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BibTeX
@misc{shick2026dynamical,
title = {{Dynamical Valence Fluctuations and Magnetic Anisotropy in Sm(Co,Cu)$_5$}},
author = {Alexander B. Shick and Alexander V. Andreev and Evgenia A. Tereshina-Chitrova and Institute of Physics and the Czech Academy of Sciences and Na Slovance 2 and CZ-18221 Prague and Czech Republic},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.06568},
eprint = {2610.06568},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.06568},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Dynamical Valence Fluctuations and Magnetic Anisotropy in Sm(Co,Cu)_5
AU - Alexander B. Shick
AU - Alexander V. Andreev
AU - Evgenia A. Tereshina-Chitrova
AU - Institute of Physics
AU - the Czech Academy of Sciences
AU - Na Slovance 2
AU - CZ-18221 Prague
AU - Czech Republic
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2610.06568
UR - https://arxiv.org/abs/2610.06568
AB - The magnetic properties of Sm-based intermetallics are governed by a delicate interplay between localized 4f states, exchange interactions, and valence fluctuations, yet the role of dynamical 4f correlations remains poorly understood. Here we investigate the electronic structure and magnetic anisotropy of SmCo_5 and SmCu_5 using self-consistent DFT+U(ED), which explicitly treats dynamical fluctuations of the Sm 4f shell. We find that SmCo_5 exhibits pronounced Sm^2+--Sm^3+ valence fluctuations, with the 4f ground state dominated by f^5 and f^6 configurations. The resulting dynamical 4f correlations yield near compensation of the Sm spin and orbital moments and provide a quantitative description of the electronic structure, magnetic moments, and large uniaxial magnetic anisotropy of SmCo_5. Upon replacing Co with Cu, the balance shifts toward the f^6 configuration, with substantial changes in the Sm spin and orbital moments. In SmCu_5, this evolution of the 4f configuration is accompanied by a pronounced reduction of both the total magnetic moment and magnetic anisotropy. These results demonstrate that dynamical 4f valence fluctuations are essential for understanding the contrasting magnetic properties of SmCo_5 and SmCu_5 and provide a microscopic framework for describing magnetic anisotropy upon Co to Cu substitution in Sm(Co,Cu)_5.
ER -