Stripes developed at the strong limit of nematicity in FeSe film

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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.


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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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