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arXiv · 1511.05418

Tunable Fe-vacancy disorder-order transition in FeSe thin films

Y. Fang·D. H. Xie·W. Zhang·F. Chen·W. Feng·B. P. Xie·D. L. Feng·X. C. Lai·S. Y. Tan
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Abstract

Various Fe-vacancy orders have been reported in tetragonal Fe1-xSe single crystals and nanowires/nanosheets, which are similar to those found in alkali metal intercalated A1-xFe2-ySe2 superconductors. Here we report the in-situ angle-resolved photoemission spectroscopy study of Fe-vacancy disordered and ordered phases in FeSe multi-layer thin films grown by molecular beam epitaxy. Low temperature annealed FeSe films are identified to be Fe-vacancy disordered phase and electron doped. Further long-time low temperature anneal can change the Fe-vacancy disordered phase to ordered phase, which is found to be semiconductor/insulator with (root 5) x (root 5) superstructure and can be reversely changed to disordered phase with high temperature anneal. Our results reveal that the disorder-order transition in FeSe thin films can be simply tuned by vacuum anneal and the (root 5) x (root 5) Fe-vacancy ordered phase is more likely the parent phase of FeSe.

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Y. Fang, D. H. Xie, W. Zhang, F. Chen, W. Feng, B. P. Xie, D. L. Feng, X. C. Lai, S. Y. Tan. 2015-11-17. Tunable Fe-vacancy disorder-order transition in FeSe thin films. https://doi.org/10.1103/physrevb.93.184503

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