发表机构
STFC; Diamond Light Source; Oxford University（STFC; 钻石光源; 牛津大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过共振X射线衍射与对称性理论，解析URhSn中间相的三角Sohncke手性结构，并用灰色群修复对称性，为kagome体系复杂相提供新见解。
AI 中文摘要
三元金属间化合物采用 ZrNiAl 型化学结构，该结构被称为 kagome 体系。这些化合物相图中观察到的复杂性归因于几何阻挫。5f 电子化合物 URhSn 在 16 K 和 54 K 处表现出两次相变。在中间温度范围（16 K - 54 K）内，中子粉末衍射图谱中未检测到超晶格反射。近期针对中间相中铀离子的共振 X 射线衍射图谱表明存在手性结构和三方 Sohncke 空间群。已确证，室温下的母相结构由六方空间群描述。研究表明，包含十六极矩的铁性序参量表征了三方 Sohncke 相。我们利用对称性-informed 理论全面研究了该相的共振 X 射线衍射。该理论通过使用灰色群修复了原始数据分析中的对称性，并解除了对铀位置施加的不合理条件。该理论采用满足求和规则的轴向原子多极矩，这些求和规则首次确立于 X 射线二色性信号中。观测与计算衍射图谱的对比支持三方 Sohncke 相的存在，并为这一神秘化合物的进一步实验研究提供了依据。
英文摘要
Ternary intermetallics use a ZrNiAl-type chemical structure known as a kagome system. Complexity observed in the phase diagrams of these compounds is attributed to the geometric frustration. The 5f-electron compound URhSn exhibits two phase transitions at 16 K and 54 K. No super-lattice reflections in neutron powder diffraction patterns are detected in the intermediate range of temperatures (16 K - 54 K). Recent resonant x-ray diffraction patterns for uranium ions in the intermediate phase suggest a chiral structure and a trigonal Sohncke space group. It is firmly established that a simple hexagonal space group describes the parent structure at room temperature. A ferroic order parameter that includes hexadecapoles is shown to characterize the trigonal Sohncke phase. Resonant x-ray diffraction by this phase is fully investigated with our symmetry informed theory. It repairs symmetry in the original data analysis by using a grey group, and it lifts an unjustified spatial condition on uranium positions. The theory uses axial atomic multipoles that satisfy sum-rules established in the first instance for x-ray dichroic signals. A confrontation between observed and calculated diffraction patterns lends support to a trigonal Sohncke phase, and exposes grounds for additional experimental work on an enigmatic compound.
