Abstract Electronic structures of the temperature-induced valence transition system EuNi2(Si1–xGex)2 with x = 0.70, 0.79, 0.82 have been investigated by means of high-energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS). The HERFD-XAS spectra clearly change their intensities of Eu2+ and Eu3+ components which directly reflect the temperature-induced valence transition. For x = 0.70, gradual spectral change exhibits a continuous valence transition, while drastic changes for x = 0.79 and 0.82 indicate first-order valence transitions. High-energy resolution measurements made it possible to observe additional fine structures which are recognized more clearly below the transition temperature. Existence of these fine structures suggests that many-body effect plays an important role in the temperature-induced valence transition of this system. The variation of Eu mean valence estimated from the HERFD-XAS spectra for each x correlates with that of magnetic susceptibility.

中文翻译：

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通过高能分辨率荧光检测 X 射线吸收光谱研究 EuNi2(Si1-Ge)2 中温度诱导的价态转变

摘要 已经通过高能分辨率荧光检测 X 射线吸收光谱 (HERFD-XAS) 研究了温度诱导的价态转变系统 EuNi2(Si1-xGex)2 的电子结构，其中 x = 0.70、0.79、0.82。HERFD-XAS 光谱明显改变了 Eu2+ 和 Eu3+ 成分的强度，这直接反映了温度引起的价态转变。对于 x = 0.70，逐渐的光谱变化表现出连续的价态跃迁，而对于 x = 0.79 和 0.82 的剧烈变化表明一阶价态跃迁。高能量分辨率测量使得观察额外的精细结构成为可能，这些结构在转变温度以下被更清楚地识别。这些精细结构的存在表明多体效应在该系统的温度诱导价转变中起着重要作用。从每个 x 的 HERFD-XAS 光谱估计的 Eu 平均价的变化与磁化率的变化相关。