• An Erratum to this article was published on 22 January 2016

This article has been updated

Abstract

In iron-based superconductors the interactions driving the nematic order (that breaks four-fold rotational symmetry in the iron plane) may also mediate the Cooper pairing1. The experimental determination of these interactions, which are believed to depend on the orbital or the spin degrees of freedom1,2,3,4, is challenging because nematic order occurs at, or slightly above, the ordering temperature of a stripe magnetic phase1,5. Here, we study FeSe (ref. 6)—which exhibits a nematic (orthorhombic) phase transition at Ts = 90 K without antiferromagnetic ordering—by neutron scattering, finding substantial stripe spin fluctuations coupled with the nematicity that are enhanced abruptly on cooling through Ts. A sharp spin resonance develops in the superconducting state, whose energy (4 meV) is consistent with an electron–boson coupling mode revealed by scanning tunnelling spectroscopy7. The magnetic spectral weight in FeSe is found to be comparable to that of the iron arsenides8,9. Our results support recent theoretical proposals that both nematicity and superconductivity are driven by spin fluctuations1,10,11,12,13.

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Change history

  • 15 December 2015

    In the original version of this Letter published online, the x axis of Fig. 2a was labelled incorrectly. In addition, tick labels have been added to the x axes of Fig. 2b and Fig. 2d. This has been corrected in all versions of the Letter.

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Acknowledgements

We thank D. H. Lee, Q. Si, F. Wang and H. Yao for useful discussions. This work is supported by the National Natural Science Foundation of China (Grant No. 11374059), the Ministry of Science and Technology of China (973 project: 2015CB921302) and the Shanghai Pujiang Scholar Program (Grant No. 13PJ1401100). M.M. and F.Z. acknowledge support from the National Natural Science Foundation of China (Grant No. 11190020). H.C. received support from the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. A.N.V. was supported in part by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST 〈MISiS〉 (No. 2-2014-036). D.A.C. and A.N.V. also acknowledge the support of the Russian Foundation for Basic Research through Grants 13-02-00174, 14-02-92002, 14-02-92693.

Author information

Affiliations

  1. State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China

    • Qisi Wang
    • , Yao Shen
    • , Bingying Pan
    • , Yiqing Hao
    •  & Jun Zhao
  2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China

    • Mingwei Ma
    •  & Fang Zhou
  3. Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France

    • P. Steffens
  4. Juelich Centre for Neutron Science JCNS Forschungszentrum Juelich GmbH, Outstation at ILL, 38042 Grenoble, France

    • K. Schmalzl
  5. European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France

    • T. R. Forrest
  6. Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China

    • M. Abdel-Hafiez
    •  & Xiaojia Chen
  7. Faculty of Science, Physics Department, Fayoum University, 63514 Fayoum, Egypt

    • M. Abdel-Hafiez
  8. Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, Moscow District 142432, Russia

    • D. A. Chareev
  9. Low Temperature Physics and Superconductivity Department, M.V. Lomonosov Moscow State University, Moscow 119991, Russia

    • A. N. Vasiliev
  10. Theoretical Physics and Applied Mathematics Department, Ural Federal University, Ekaterinburg 620002, Russia

    • A. N. Vasiliev
  11. National University of Science and Technology “MISiS”, Moscow 119049, Russia

    • A. N. Vasiliev
  12. Laboratoire Leon Brillouin, CEA-CNRS, CEA-Saclay, 91191 Gif sur Yvette, France

    • P. Bourges
    •  & Y. Sidis
  13. Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA

    • Huibo Cao
  14. Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China

    • Jun Zhao

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Contributions

J.Z. planned the project. M.M., F.Z., D.A.C. and A.N.V. synthesized the sample. Q.W., Y. Shen, B.P., Y.H., M.A.-H. and X.C. characterized the sample. Q.W. and Y. Shen. carried out the neutron experiments with experimental assistance from P.S., K.S., T.R.F., P.B., Y. Sidis and H.C. J.Z. and Q.W. analysed the data and wrote the paper. All authors provided comments for the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jun Zhao.

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DOI

https://doi.org/10.1038/nmat4492

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