Dispersionless orbital excitations in (Li,Fe)OHFeSe superconductors
Dispersionless orbital excitations in (Li,Fe)OHFeSe superconductors
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DOI：
10.1038/s41535-022-00492-0
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发表时间：
2022-08
影响因子：
5.7
通讯作者：
Qian Xiao;Wenliang Zhang;T. Asmara;Dong Li;Qizhi Li;Shi-Yue Zhang;Y. Tseng;Xiaoli Dong;
中科院分区：
文献类型：
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作者：
Qian Xiao;Wenliang Zhang;T. Asmara;Dong Li;Qizhi Li;Shi-Yue Zhang;Y. Tseng;Xiaoli Dong;
在（Li，Fe）OHFeSe（FeSe 11111）中加入铁硒化物，可使其超导临界温度Tc从体相FeSe的8 K提高到42.它显示出与高Tc单层FeSe非常相似的电子性质，并为研究增强的超导电性的起源提供了体相。揭示激发的本质对于理解高Tciron硒化物中的配对机制至关重要。在这里，我们使用共振非弹性X射线散射（RIXS）调查的激发FeSe 11111。我们的高质量的数据表现出几个拉曼类激发，这是分散和各向同性的动量转移在超导28 K和42 K样品。使用原子多重态计算，我们指定的低能~0.3和0.7 eV的拉曼峰为localeg−egandeg− t2 gorbital激发。这两个特征的强度随着温度的升高而降低，表明轨道波动的主要贡献。我们的研究结果突出了高Tciron硒化物的轨道自由度的重要性。
The superconducting critical temperatureTcof intercalated iron-selenide superconductor (Li,Fe)OHFeSe (FeSe11111) can be increased to 42 from 8 K of bulk FeSe. It shows remarkably similar electronic properties as the high-Tcmonolayer FeSe and provides a bulk counterpart to investigate the origin of enhanced superconductivity. Unraveling the nature of excitations is crucial for understanding the pairing mechanism in high-Tciron selenides. Here we use resonant inelastic x-ray scattering (RIXS) to investigate the excitations in FeSe11111. Our high-quality data exhibit several Raman-like excitations, which are dispersionless and isotropic in momentum transfer in both superconducting 28 K and 42 K samples. Using atomic multiplet calculations, we assign the low-energy ~0.3 and 0.7 eV Raman peaks as localeg−egandeg−t2gorbital excitations. The intensity of these two features decreases with increasing temperature, suggesting a dominating contribution of the orbital fluctuations. Our results highlight the importance of the orbital degree of freedom for high-Tciron selenides.