发表机构
Institute of Physics, the Czech Academy of Sciences（捷克科学院物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过DFT+U(ED)方法研究SmCo$_5$和SmCu$_5$，揭示动态4f价态涨落主导磁性差异，并定量解释磁各向异性变化。
AI 中文摘要
Sm基金属间化合物的磁性由局域 $4f$ 态、交换相互作用和价态涨落之间的微妙竞争所决定，然而动态 $4f$ 关联的作用仍未被充分理解。本文利用自洽 DFT+$U$(ED) 方法研究 SmCo$_5$ 和 SmCu$_5$ 的电子结构与磁各向异性，该方法显式处理 Sm $4f$ 壳层的动态涨落。我们发现 SmCo$_5$ 表现出显著的 Sm$^{2+}$--Sm$^{3+}$ 价态涨落，其中 $4f$ 基态由 $f^5$ 和 $f^6$ 构型主导。由此产生的动态 $4f$ 关联导致 Sm 自旋矩与轨道矩近乎相互抵消，并为 SmCo$_5$ 的电子结构、磁矩以及大的单轴磁各向异性提供了定量描述。当用 Cu 替代 Co 时，平衡向 $f^6$ 构型移动，Sm 自旋矩和轨道矩发生显著变化。在 SmCu$_5$ 中，$4f$ 构型的这种演变伴随着总磁矩和磁各向异性的显著降低。这些结果表明，动态 $4f$ 价态涨落对于理解 SmCo$_5$ 和 SmCu$_5$ 截然不同的磁性至关重要，并为描述 Sm(Co,Cu)$_5$ 中 Co 到 Cu 替代时的磁各向异性提供了微观框架。
英文摘要
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)$_5$.
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