AI 中文总结
研究金红石型交替磁体CoF₂，结合共振弹性X射线散射等方法发现其反铁四极序为交替磁性微观起源，该方法可用于一般交替磁体研究。
AI 中文摘要
交替磁体具有非相对论性自旋分裂电子态，其微观起源理论上与隐藏的电荷序相关，但对该电荷序的实验研究有限。为此，我们研究了金红石晶体结构、Γ点反铁磁性的d波交替磁体化合物CoF₂中的电荷序。结合共振弹性X射线散射、对称性分析和从头算，我们直接观测到电荷序并确定其本质为反铁四极序。通过电子结构计算，我们表明实验观测到的反铁四极序会产生交替磁体特有的自旋分裂，从而为交替磁体序参数分解为磁性和电荷自由度提供了经验证据。我们由此证明，反铁四极序是CoF₂中交替磁性的微观起源，对更广泛的金红石型交替磁体系列具有意义。此外，我们的方法适用于一般交替磁体的研究，已证明共振弹性X射线散射可作为探测这些材料中支撑自旋分裂电子态的电荷多极的直接手段。
英文摘要
Altermagnets host non-relativistic spin-split electronic states whose microscopic origin is theoretically linked to a hidden charge order, yet experimental studies of this charge order are limited. We therefore investigate charge order within CoF$_2$, a $d$-wave altermagnetic compound with a rutile crystal structure and $Γ$-point antiferromagnetism. Combining resonant elastic X-ray scattering, symmetry analysis and ab initio calculations, we directly observe charge ordering and identify it as antiferroquadrupolar in nature. Via electronic structure calculations, we show that the experimentally observed antiferroquadrupolar order gives rise to the characteristic altermagnetic spin-splitting, thereby establishing empirical evidence for the decomposition of the altermagnetic order parameter into magnetic and charge degrees of freedom. We hence demonstrate that antiferroquadrupolar order is the microscopic origin of altermagnetism in CoF$_2$, with implications to the wider family of rutile altermagnets. Furthermore, our approach is applicable to studying altermagnetism in general, having demonstrated that resonant elastic X-ray scattering can serve as a direct probe of the charge multipoles that underpin spin-split electronic states in these materials.
