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Phase diagram and electronic indication of high-temperature superconductivity at 65 K in single-layer FeSe films

Nature Materials volume 12, pages 605–610 (2013)Cite this article

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Abstract

The recent discovery of possible high-temperature superconductivity in single-layer FeSe films1,2 has generated significant experimental and theoretical interest3,4. In both the cuprate5,6 and the iron-based7,8,9,10,11 high-temperature superconductors, superconductivity is induced by doping charge carriers into the parent compound to suppress the antiferromagnetic state. It is therefore important to establish whether the superconductivity observed in the single-layer sheets of FeSe—the essential building blocks of the Fe-based superconductors—is realized by undergoing a similar transition. Here we report the phase diagram for an FeSe monolayer grown on a SrTiO3 substrate, by tuning the charge carrier concentration over a wide range through an extensive annealing procedure. We identify two distinct phases that compete during the annealing process: the electronic structure of the phase at low doping (N phase) bears a clear resemblance to the antiferromagnetic parent compound of the Fe-based superconductors, whereas the superconducting phase (S phase) emerges with the increase in doping and the suppression of the N phase. By optimizing the carrier concentration, we observe strong indications of superconductivity with a transition temperature of 65±5 K. The wide tunability of the system across different phases makes the FeSe monolayer ideal for investigating not only the physics of superconductivity, but also for studying novel quantum phenomena more generally.

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Figure 1: Fermi surface evolution of the single-layer FeSe film during the annealing process.
Figure 2: Band structure evolution of the single-layer FeSe film during the annealing process.
Figure 3: Temperature dependence of the energy gap of the single-layer FeSe film annealed under different conditions.
Figure 4: Schematic phase diagram of the single-layer FeSe film during the annealing process.

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Acknowledgements

We thank D-H. Lee and Z-X. Shen for discussions. X.J.Z. acknowledges financial support from the NSFC (10734120) and the MOST of China (973 programme No: 2011CB921703 and 2011CB605903). Q.X. and X.M. acknowledge support from the MOST of China (programme No. 2009CB929400 and No. 2012CB921702).

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  1. Shaolong He, Junfeng He, Wenhao Zhang and Lin Zhao: These authors contributed equally to this work

Authors and Affiliations

  1. National Lab for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

    Shaolong He, Junfeng He, Lin Zhao, Defa Liu, Xu Liu, Daixiang Mou, Yingying Peng, Yan Liu, Chaoyu Chen, Li Yu, Guodong Liu, Xiaoli Dong, Jun Zhang & X. J. Zhou

  2. Department of Physics, State Key Lab of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China

    Wenhao Zhang, Qing-Yan Wang, Xi Chen & Qikun Xue

  3. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

    Wenhao Zhang, Yun-Bo Ou, Qing-Yan Wang, Zhi Li, Lili Wang & Xucun Ma

  4. Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China

    Chuangtian Chen & Zuyan Xu

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  1. Shaolong He
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Contributions

S.H., J.H., W.Z. and L.Z. contributed equally to this work. X.J.Z., Q.X. and X.M. proposed and designed the research. W.Z., Y-B.O, Q-Y.W., Z.L., L.W., X.C., X.C.M and Q.X. contributed to MBE thin-film preparation. S.H., J.H., L.Z., D.L., X.L., D.M., Y.P., Y.L., C.C., L.Y., G.L., X.D., J.Z., C.C., Z.X. and X.J.Z. contributed to the development and maintenance of the laser-ARPES system. S.H., J.H., W.Z., L.Z., D.L., X.L. and Y-B.O. carried out the experiment. S.H., J.H., L.Z., D.L., X.L. and X.J.Z. analysed the data. X.J.Z. wrote the paper with J.H., S.H., L.Z., D.L, X.L., X.M. and Q.X.

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Correspondence to Xucun Ma, Qikun Xue or X. J. Zhou.

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He, S., He, J., Zhang, W. et al. Phase diagram and electronic indication of high-temperature superconductivity at 65 K in single-layer FeSe films. Nature Mater 12, 605–610 (2013). https://doi.org/10.1038/nmat3648

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