Abstract We have investigated the local structure of layered La 1 − x Ce x OBiSSe system by Bi L 3 -edge extended X-ray absorption fine structure (EXAFS) measurements for different Ce substitutions. Ce L 3 -edge X-ray absorption spectroscopy (XAS) has been used to evaluate the Ce valence responsible for the self-doping in this system. We have found that the local distortion, determined by the separation between two Bi-Ch distances within the BiCh 2 -layer (Ch=S,Se), is quickly suppressed by Ce substitution while the axial Bi-S2 bond elongates. Ce L 3 -edge XAS reveals a coexistence of Ce 3 + and Ce 4 + in which the Ce 4 + weight decreases, an indication of a partial breaking of R E -S-Bi ( R E =La/Ce) charge transfer channel with Ce substitution. The results suggest that interaction between R E O spacer layer and BiCh 2 layer, dictated by the out-of-plane Bi-S2 distance, has a significant role in triggering superconductivity in the title system, with the in-plane distortion controlling the charge mobility within the BiCh 2 -layer.

中文翻译：

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La1−xCexOBiSSe 中的局部结构位移作为 Ce 取代的函数

摘要 我们通过 Bi L 3 边缘扩展 X 射线吸收精细结构 (EXAFS) 测量研究了层状 La 1 - x Ce x OBiSSe 系统的局部结构，用于不同的 Ce 取代。Ce L 3 边缘X射线吸收光谱(XAS)已被用于评估负责该系统中自掺杂的Ce价。我们发现局部畸变由 BiCh 2 层内的两个 Bi-Ch 距离之间的间隔决定 (Ch=S,Se)，在轴向 Bi-S2 键伸长时被 Ce 取代迅速抑制。Ce L 3 -edge XAS 揭示了 Ce 3 + 和 Ce 4 + 的共存，其中 Ce 4 + 重量减少，表明 RE -S-Bi ( RE = La/Ce) 电荷转移通道与 Ce 部分断裂代换。结果表明 REO 间隔层和 BiCh 2 层之间的相互作用，