Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films

S. Y. Tan; M. Xia; Y. Zhang; Z. R. Ye; F. Chen; X. Xie; R. Peng; D. F. Xu; Q. Fan; H. C. Xu; J. Juan; T. Zhang; X. C. Lai; T. Xiang; J. P. Hu; B. P. Xie; D. L. Feng

doi:10.1038/nmat3654

arXiv · 1301.2748

Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films

S. Y. Tan·M. Xia·Y. Zhang·Z. R. Ye·F. Chen·X. Xie·R. Peng·D. F. Xu·Q. Fan·H. C. Xu·J. Juan·T. Zhang·X. C. Lai·T. Xiang·J. P. Hu·B. P. Xie·D. L. Feng

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Abstract

The record of superconducting transition temperature(Tc) has long been 56K for the iron-based high temperature superconductors(Fe-HTS's). Recently, in single layer FeSe films grown on SrTiO3 substrate, signs for a new 65K Tc record are reported. Here with in-situ photoemission measurements, we substantiate the presence of the spin density wave(SDW) in FeSe films, a key ingredient of Fe-HTS that was missed in FeSe before, which weakens with increased thickness or reduced strain. We demonstrate that the superconductivity occurs when the electrons transferred from the oxygen-vacant substrate suppress the otherwise most pronounced SDW in single layer FeSe. Besides providing a comprehensive understanding of FeSe films and directions to further enhance its Tc, we establish the phase diagram of FeSe vs. lattice constant that contains all the essential physics of Fe-HTS's. With the simplest structure, cleanest composition and single tuning parameter, it is ideal for testing theories of Fe-HTS's.

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S. Y. Tan, M. Xia, Y. Zhang, Z. R. Ye, F. Chen, X. Xie, R. Peng, D. F. Xu, Q. Fan, H. C. Xu, J. Juan, T. Zhang, X. C. Lai, T. Xiang, J. P. Hu, B. P. Xie, D. L. Feng. 2013-01-13. Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films. https://doi.org/10.1038/nmat3654

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