文章基本信息

标题：Evolution of superconductivity in K2−xFe4+ySe5: Spectroscopic studies of X-ray absorption and emission
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作者：H. T. Wang ; Anirudha Ghosh ; C. H. Wang 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：45
页码：22458-22463
DOI：10.1073/pnas.1912610116
出版社：The National Academy of Sciences of the United States of America
摘要：This study investigates the evolution of superconductivity in K 2−x Fe 4+y Se 5 using temperature-dependent X-ray absorption and resonant inelastic X-ray scattering techniques. Magnetization measurements show that polycrystalline superconducting (SC) K 1.9 Fe 4.2 Se 5 has a critical temperature ( T c ) of ∼31 K with a varying superconducting volume fraction, which strongly depends on its synthesis temperature. An increase in Fe-structural/vacancy disorder in SC samples with more Fe atoms occupying vacant 4d sites is found to be closely related to the decrease in the spin magnetic moment of Fe. Moreover, the nearest-neighbor Fe–Se bond length in SC samples exceeds that in the non-SC (NS) sample, K 2 Fe 4 Se 5 , which indicates a weaker hybridization between the Fe 3 d and Se 4 p states in SC samples. These results clearly demonstrate the correlations among the local electronic and atomic structures and the magnetic properties of K 2−x Fe 4+y Se 5 superconductors, providing deeper insight into the electron pairing mechanisms of superconductivity..
关键词：superconductivity ; Fe vacancy disorder ; X;ray absorption spectroscopy ; resonant inelastic X;ray scattering