5d-mediated indirect exchange and effective spin Hamiltonians in Ce triangular-lattice delafossites
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866913103956934656 |
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| author | Pourovskii, Leonid V. |
| author_facet | Pourovskii, Leonid V. |
| contents | Anisotropic intersite exchange interactions in frustrated rare-earth magnets are difficult to assess both theoretically and experimentally. Here, we propose an ab initio force-theorem framework combining the quasi-atomic Hubbard-I approach to 4f correlations with a static mean-field treatment of the on-site intershell Coulomb interaction between rare-earth 4f and 5d states to simultaneously capture both 4f superexchange and 5d-mediated indirect exchange. Applying it to the triangular lattice Ce delafossites CsCeSe$_2$, KCeS$_2$, and RbCeO$_2$, we find that the indirect exchange dominates in the selenide, the superexchange in the oxide, while both mechanisms contribute almost equally in the sulfide. The magnetic exciation spectra of CsCeSe$_2$ and KCeS$_2$ evaluated from the calculated spin Hamiltonains are in good qualitative and quantitative agreement with experimental data. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_14904 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | 5d-mediated indirect exchange and effective spin Hamiltonians in Ce triangular-lattice delafossites Pourovskii, Leonid V. Strongly Correlated Electrons Materials Science Anisotropic intersite exchange interactions in frustrated rare-earth magnets are difficult to assess both theoretically and experimentally. Here, we propose an ab initio force-theorem framework combining the quasi-atomic Hubbard-I approach to 4f correlations with a static mean-field treatment of the on-site intershell Coulomb interaction between rare-earth 4f and 5d states to simultaneously capture both 4f superexchange and 5d-mediated indirect exchange. Applying it to the triangular lattice Ce delafossites CsCeSe$_2$, KCeS$_2$, and RbCeO$_2$, we find that the indirect exchange dominates in the selenide, the superexchange in the oxide, while both mechanisms contribute almost equally in the sulfide. The magnetic exciation spectra of CsCeSe$_2$ and KCeS$_2$ evaluated from the calculated spin Hamiltonains are in good qualitative and quantitative agreement with experimental data. |
| title | 5d-mediated indirect exchange and effective spin Hamiltonians in Ce triangular-lattice delafossites |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2511.14904 |