Stripes developed at the strong limit of nematicity in FeSe film

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Abstract

A single monolayer of iron selenide grown on strontium titanate shows an impressive enhancement of superconductivity compared with the bulk1, as well as a novel Fermi surface topology2,3,4,5, extreme two-dimensionality, and the possibility of phonon-enhanced electron pairing1,5. For films thicker than one unit cell, however, the electronic structure is markedly different, with a drastically suppressed superconductivity and strong nematicity appearing. The physics driving this extraordinary dichotomy of superconducting behaviour is far from clear. Here, we use low-temperature scanning tunnelling microscopy to study multilayers of iron selenide grown by molecular beam epitaxy, and find a stripe-type charge ordering instability that develops beneath the nematic state. The charge ordering is visible and pinned in the vicinity of impurities. And as it emerges in the strong limit of nematicity, it suggests that a magnetic fluctuation with a rather small wavevector may be competing with the ordinary collinear antiferromagnetic ordering in multilayer films. The existence of stripes in iron-based superconductors, which resemble the stripe order in cuprates, not only suggests that electronic anisotropy and correlation are playing an important role, but also provides a platform for probing the complex interactions between nematicity, charge ordering, magnetism and superconductivity in high-temperature superconductors.

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Figure 1: MBE film and C2 domains of FeSe.
Figure 2: Bias voltage dependence of the stripes in the vicinity of the impurities.
Figure 3: Charge ordering origin of the stripes.
Figure 4: Temperature dependence of the stripes and the C2 domain walls.
Figure 5: The interaction between the stripes and the impurity states.

References

  1. 1

    Wang, Q. Y. et al. Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3 . Chin. Phys. Lett. 29, 037402 (2012).

  2. 2

    Liu, D. F. et al. Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor. Nat. Commun. 3, 931 (2012).

  3. 3

    Tan, S. Y. et al. Interface-induced superconductivity and strain-dependent spin density waves in FeSe/SrTiO3 thin films. Nat. Mater. 12, 634–640 (2013).

  4. 4

    He, S. L. et al. Phase diagram and electronic indication of high-temperature superconductivity at 65 K in single-layer FeSe films. Nat. Mater. 12, 605–610 (2013).

  5. 5

    Lee, J. J. et al. Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3 . Nature 515, 245–248 (2014).

  6. 6

    Kivelson, S. A., Fradkin, E. & Emery, V. J. Electronic liquid-crystal phases of a doped Mott insulator. Nature 393, 550–553 (1998).

  7. 7

    Zhao, J. et al. Spin waves and magnetic exchange interactions in CaFe2As2 . Nat. Phys. 5, 555–560 (2009).

  8. 8

    Chu, J. H. et al. In-plane resistivity anisotropy in an underdoped iron arsenide superconductor. Science 329, 824–826 (2010).

  9. 9

    Chuang, T.-M. et al. Nematic electronic structure in the ‘parent’ state of the iron-based superconductor Ca(Fe1−xCox)2As2 . Science 327, 181–184 (2010).

  10. 10

    Kasahara, S. Electronic nematicity above the structural and superconducting transition in BaFe2(As1−xPx)2 . Nature 486, 382–385 (2012).

  11. 11

    Yi, M. et al. Symmetry-breaking orbital anisotropy observed for detwinned Ba(Fe1−xCox)2As2 above the spin density wave transition. Proc. Natl Acad. Sci. USA 108, 6878–6883 (2011).

  12. 12

    Rosenthal, E. P. et al. Visualization of electron nematicity and unidirectional antiferroic fluctuations at high temperatures in NaFeAs. Nat. Phys. 10, 225–232 (2014).

  13. 13

    Tanatar, M. A. et al. Uniaxial-strain mechanical detwinning of CaFe2As2 and BaFe2As2 crystals: optical and transport study. Phys. Rev. B 81, 184508 (2010).

  14. 14

    Lee, C.-C., Yin, W. G. & Ku, W. Ferro-orbital order and strong magnetic anisotropy in the parent compounds of iron-pnictide superconductors. Phys. Rev. Lett. 103, 267001 (2009).

  15. 15

    Nakayama, K. et al. Reconstruction of band structure induced by electronic nematicity in an FeSe superconductor. Phys. Rev. Lett. 113, 237001 (2014).

  16. 16

    Borisenko, S. V. et al. Direct observation of spin–orbit coupling in iron-based superconductors. Nat. Phys. 12, 311–317 (2016).

  17. 17

    Watson, M. D. et al. Evidence for unidirectional nematic bond ordering in FeSe. Phys. Rev. B 94, 201107(R) (2016).

  18. 18

    Zhang, Y. et al. Distinctive orbital anisotropy observed in the nematic state of a FeSe thin film. Phys. Rev. B 94, 115153 (2016).

  19. 19

    Hsu, F. C. et al. Superconductivity in the PbO-type structure α-FeSe. Proc. Natl Acad. Sci. USA 105, 14262–14264 (2008).

  20. 20

    Bendele, M. et al. Coexistence of superconductivity and magnetism in FeSe1−x under pressure. Phys. Rev. B 85, 064517 (2012).

  21. 21

    Sun, J. P. et al. Dome-shaped magnetic order competing with high-temperature superconductivity at high pressures in FeSe. Nat. Commun. 7, 12146 (2016).

  22. 22

    Kothapalli, K. et al. Strong cooperative coupling of pressure-induced magnetic order and nematicity in FeSe. Nat. Commun. 7, 12728 (2016).

  23. 23

    Song, C.-L. et al. Suppression of superconductivity by twin boundaries in FeSe. Phys. Rev. Lett. 109, 137004 (2012).

  24. 24

    Kasahara, S. et al. Field-induced superconducting phase of FeSe in the BCS-BEC cross-over. Proc. Natl Acad. Sci. USA 111, 16309–16313 (2014).

  25. 25

    Huang, D. et al. Dumbbell defects in FeSe films: a scanning tunneling microscopy and first-principles investigation. Nano Lett. 16, 4224 (2016).

  26. 26

    Inoue, Y., Yamakawa, Y. & Kontani, H. Impurity-induced electronic nematic state and C2-symmetric nanostructures in iron pnictide superconductors. Phys. Rev. B 85, 224506 (2012).

  27. 27

    Tam, Y.-T., Yao, D.-X. & Wei, K. Itinerancy-enhanced quantum fluctuation of magnetic moments in iron-based superconductors. Phys. Rev. Lett. 115, 117001 (2015).

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Acknowledgements

We thank T. Li, H. Yao and J. P. Hu for discussions. STM work was supported by the National Science Foundation (No. 11674191) and Ministry of Science and Technology of China (No. 2016YFA0301002). W.L. was also supported by Beijing Young Talents Plan. ALS and SSRL are operated by the Office of Basic Energy Sciences, US DOE, under Contracts No. DE-AC02-05CH11231 and No. DE-AC02-76SF00515, respectively. The Stanford work is supported by the US DOE, Office of Basic Energy Science, Division of Materials Science and Engineering, under award number DE-AC02-76SF00515.

Author information

W.L., P.D., Z.X. and H.D. carried out the STM experiments; W.L. and Y.Z. performed the ARPES experiments; W.L., X.C. and Z.-X.S. designed and coordinated the experiments; D.-H.L. and M.H. provided experimental support at Stanford Synchrotron Radiation Lightsource. S.K.-M. provided experimental support at Advanced Light Source. Y.Z., D.-H.L., M.Y. and R.G.M. provided discussion about data and interpretation. Q.-K.X. oversaw the project. W.L. wrote the manuscript with comments from all authors.

Correspondence to Wei Li or Xi Chen or Z.-X. Shen.

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Li, W., Zhang, Y., Deng, P. et al. Stripes developed at the strong limit of nematicity in FeSe film. Nature Phys 13, 957–961 (2017) doi:10.1038/nphys4186

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