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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2410.11256 |
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| _version_ | 1866918367918555136 |
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| author | Tanaka, Tomonori Gohda, Yoshihiro |
| author_facet | Tanaka, Tomonori Gohda, Yoshihiro |
| contents | Exchange coupling parameters $J_{ij}$ in the Heisenberg model are crucial for describing magnetic behavior at the atomic level. In magnetic materials, spin fluctuations can be accompanied by a self-consistent electronic response -- including charge and magnetization redistribution and changes in orbital occupations -- reflecting electron--spin coupling in the sense of electronic feedback to finite spin rotations. However, the quantitative importance of this coupling in extracting reliable $J_{ij}$ has not been fully clarified. Here, using fully self-consistent, nonperturbative evaluations, we show that finite-angle spin rotations induce such electronic feedback and quantify how strongly it renormalizes the extracted $J_{ij}$. We examine systems of both fundamental and practical interest, including perovskite SrMnO$_3$, Nd-based permanent-magnet compounds (Nd$_2$Fe$_{14}$B and Nd$_2$Co$_{14}$B), and elemental $3d$ transition metals.The nonperturbative approach yields exchange couplings that remain consistent over a wide range of rotation angles. Moreover, spin models parameterized in this way give reasonable agreement with experimental magnetic phase-transition temperatures, underscoring the quantitative role of electron--spin coupling. Overall, our results provide a practical route to constructing quantitatively reliable spin models for predictive finite-temperature simulations and magnetic-materials design. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_11256 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Impact of electron--spin coupling on exchange coupling parameters: a nonperturbative approach Tanaka, Tomonori Gohda, Yoshihiro Materials Science Exchange coupling parameters $J_{ij}$ in the Heisenberg model are crucial for describing magnetic behavior at the atomic level. In magnetic materials, spin fluctuations can be accompanied by a self-consistent electronic response -- including charge and magnetization redistribution and changes in orbital occupations -- reflecting electron--spin coupling in the sense of electronic feedback to finite spin rotations. However, the quantitative importance of this coupling in extracting reliable $J_{ij}$ has not been fully clarified. Here, using fully self-consistent, nonperturbative evaluations, we show that finite-angle spin rotations induce such electronic feedback and quantify how strongly it renormalizes the extracted $J_{ij}$. We examine systems of both fundamental and practical interest, including perovskite SrMnO$_3$, Nd-based permanent-magnet compounds (Nd$_2$Fe$_{14}$B and Nd$_2$Co$_{14}$B), and elemental $3d$ transition metals.The nonperturbative approach yields exchange couplings that remain consistent over a wide range of rotation angles. Moreover, spin models parameterized in this way give reasonable agreement with experimental magnetic phase-transition temperatures, underscoring the quantitative role of electron--spin coupling. Overall, our results provide a practical route to constructing quantitatively reliable spin models for predictive finite-temperature simulations and magnetic-materials design. |
| title | Impact of electron--spin coupling on exchange coupling parameters: a nonperturbative approach |
| topic | Materials Science |
| url | https://arxiv.org/abs/2410.11256 |