CeFe$_2$中混合价态磁性的多杂质DFT+DMFT研究

中文摘要 AI 辅助

CeFe$_2$中磁性的微观起源近四十年来一直未得到解决，其中极化中子衍射和X射线磁圆二色性推断出显著不同的Ce $4f$自旋和轨道矩，且这些结果也与理论不一致。我们在此表明，在相对论性多杂质DFT+DMFT框架内，其中Fe $3d$态通过自旋极化T矩阵涨落交换处理，Ce $4f$轨道通过浴耦合组态相互作用求解器处理，这一长期问题得以解决。该理论水平在再现Ce和Fe原子的磁矩（自旋和轨道）方面具有独特性，得出的总矩与测量的饱和矩一致。与极化中子衍射的值相比，本文提出的理论与XMCD报告的原子特定矩更为接近。占据数$\langle n_f\rangle=0.85$和电荷方差$\delta n_f^2=0.27$确立了显著的价态涨落，而谱函数同时恢复了费米能级处的显著权重以及分离的非相干结构。这些结果确定了浴介导的极化和组态混合是控制CeFe$_2$电子结构和磁性的基本要素。

英文摘要

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 $\langle n_f\rangle=0.85$ 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$_2$.

发表机构

• Uppsala University（乌普萨拉大学）
• Wallenberg Initiative Materials Science (WISE), Uppsala University（乌普萨拉大学瓦伦伯格材料科学倡议）

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