发表机构
Universidade de São Paulo; Goethe-University Frankfurt（圣保罗大学; 法兰克福歌德大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究结合局域稀土磁矩与巡游过渡金属子晶格材料的磁序，利用太赫兹光谱分辨相关模式，通过其耦合演化量化内部场，揭示Gd有序转变，建立统一框架获取量子材料磁与晶格响应。
AI 中文摘要
结合局域稀土磁矩和巡游过渡金属子晶格的材料中的磁序会产生内部场，其晶格印记很少能直接获取。在钆烧绿石钌酸盐中，我们发现单一太赫兹光谱能分辨出交换分裂的Gd³⁺模式和光学声子。它们的耦合演化量化了内部场，揭示了体热力学探针难以探测到的Gd有序转变，为获取相关量子材料中的磁响应和晶格响应建立了统一框架。
英文摘要
Magnetic order carried by higher-rank multipoles produces no net moment and couples only weakly to conventional dipolar probes. Recently, the lattice has been proposed as an alternative detection channel for the associated ordering transitions. Here we report magneto-terahertz time-domain spectroscopy of the pyrochlore ruthenate Gd$_2$Ru$_2$O$_7$, in which a single spectrum resolves an exchange-split Gd$^{3+}$ transition and an infrared-active optical phonon. The temperature and field dependence of the magnetic mode give two independent determinations of the internal exchange field at the rare-earth site, which yield a magnitude of 5-6 T and a free-ion $g$-factor. The optical phonon, sensitive to spin-disorder scattering rather than to the static exchange field, exhibits a sharp anomaly in frequency and lifetime at 10 K that shifts to 30 K under 7 T, which we identify as an ordering transition of the Gd sublattice hidden from bulk thermodynamic probes. These results identify spin-phonon coupling as a route to rare-earth ordering transitions in multipolar magnets, one that is applicable to polycrystalline samples.
Comments10 pages including supplemental material
