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Topological edge states in a high-temperature superconductor FeSe/SrTiO3(001) film

Nature Materials volume 15, pages 968–973 (2016)Cite this article

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Abstract

Superconducting and topological states are two most intriguing quantum phenomena in solid materials. The entanglement of these two states, the topological superconducting state, will give rise to even more exotic quantum phenomena. While many materials are found to be either a superconductor or a topological insulator, it is very rare that both states exist in one material. Here, we demonstrate by first-principles theory as well as scanning tunnelling spectroscopy and angle-resolved photoemission spectroscopy experiments that the recently discovered ‘two-dimensional (2D) superconductor’ of single-layer FeSe also exhibits 1D topological edge states within an energy gap of ∼40 meV at the M point below the Fermi level. It is the first 2D material that supports both superconducting and topological states, offering an exciting opportunity to study 2D topological superconductors through the proximity effect.

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Figure 1: Theoretical atomic structure, band structure and quantized spin Hall conductance.
Figure 2: Band-structure comparison between theory and second-derivative ARPES spectra.
Figure 3: Theoretical topological edge state of FeSe/STO.
Figure 4: Topological edge state comparison between theory and STS spectra.

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Acknowledgements

Z.F.W. and F.Liu acknowledge financial support from DOE-BES (No. DE-FG02-04ER46148). Z.F.W. acknowledges additional financial support from the Chinese Youth 1000 Talents Program and Fundamental Research Funds for the Central Universities. X.J.Z. acknowledges financial support from the NSFC (No. 11190022 and 11334010) and the Strategic Priority Research Program (B) of CAS (No. XDB07020300). Q.K.X. and X.M. acknowledge financial support from the MOST of China (No. 2009CB929400 and 2012CB921702). We also thank the Supercomputing Center at USTC, NERSC and CHPC at University of Utah for providing the computing resources.

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Author notes

  1. Z. F. Wang and Huimin Zhang: These authors contributed equally to this work.

Authors and Affiliations

  1. Hefei National Laboratory for Physical Sciences at the Microscale, Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China

    Z. F. Wang

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

    Z. F. Wang, Huimin Zhang, Chong Liu, Chenjia Tang, Canli Song, Yong Zhong, Junping Peng, Fangsen Li, Caina Nie, Lili Wang, Xucun Ma, Q. K. Xue & Feng Liu

  3. Department of Materials Science and Engineering, University of Utah, Utah 84112, USA

    Z. F. Wang & Feng Liu

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

    Huimin Zhang, Junping Peng, Caina Nie & Xucun Ma

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

    Defa Liu & X. J. Zhou

  6. Collaborative Innovation Center of Quantum Matter, Beijing 100084, China

    Lili Wang, X. J. Zhou, Xucun Ma, Q. K. Xue & Feng Liu

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  1. Z. F. Wang
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Contributions

Z.F.W. and F.Liu conceived the project, and Z.F.W. carried out the theoretical calculation. H.Z., C.L., C.T., C.S., Y.Z., J.P., F.Li, C.N., L.W., X.M. and Q.K.X. carried out the MBE thin-film growth and STS measurement. D.L. and X.J.Z. carried out the ARPES measurement. Z.F.W. and F.Liu prepared the manuscript with input from X.J.Z., X.M. and Q.K.X.

Corresponding authors

Correspondence to X. J. Zhou, Xucun Ma or Feng Liu.

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Wang, Z., Zhang, H., Liu, D. et al. Topological edge states in a high-temperature superconductor FeSe/SrTiO3(001) film. Nature Mater 15, 968–973 (2016). https://doi.org/10.1038/nmat4686

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