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摘要
The spatial relationship of the intrinsic chemical inhomogeneity of Te, Se, and the interstitial iron (iron in 2c Wyckoff sites Fe(2)) in the Fe1+yTe1-xSex system has been studied in this work with the state-of-the-art aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM). By comparing two highly epitaxial Fe1+yTe1-xSex films prepared by standard pulse-laser deposition, we found that the film growth atmosphere can greatly affect the stoichiometry, the homogeneity of Se/Te ordering, and thus superconducting properties. For the first time, the local atomic arrangement of the Te and Se as well as Fe(2) has been clearly revealed. Films grown in a vacuum environment exhibit near-randomly distributed Se/Te and highly localized Fe(2), with a relatively higher superconducting transition temperature. The significance of the chemical inhomogeneity has been discussed in relation to the scale of the coherence length in iron chalcogenide superconductors.
- 出版日期2013-4-11
