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Fully gapped topological surface states in Bi2Se3 films induced by a d-wave high-temperature superconductor

Nature Physics volume 9, pages 621625 (2013) | Download Citation

Abstract

Topological insulators are a new class of material1,2, that exhibit robust gapless surface states protected by time-reversal symmetry3,4. The interplay of such symmetry-protected topological surface states and symmetry-broken states (for example, superconductivity) provides a platform for exploring new quantum phenomena and functionalities, such as one-dimensional chiral or helical gapless Majorana fermions5, and Majorana zero modes6 that may find application in fault-tolerant quantum computation7,8. Inducing superconductivity on the topological surface states is a prerequisite for their experimental realization1,2. Here, by growing high-quality topological insulator Bi2Se3 films on a d-wave superconductor Bi2Sr2CaCu2O8+δ using molecular beam epitaxy, we are able to induce high-temperature superconductivity on the surface states of Bi2Se3 films with a large pairing gap up to 15 meV. Interestingly, distinct from the d-wave pairing of Bi2Sr2CaCu2O8+δ, the proximity-induced gap on the surface states is nearly isotropic and consistent with predominant s-wave pairing as revealed by angle-resolved photoemission spectroscopy. Our work could provide a critical step towards the realization of the long sought Majorana zero modes.

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Acknowledgements

We thank L. Fu, D-H. Lee, S. Kivelson and S. Zhang for useful discussions. This work is supported by the National Natural Science Foundation of China (grant No. 11274191 and 11025419) and Ministry of Education of China (20121087903, 20121778394). H.Y. and S.Z. acknowledges the support from the National Thousand Young Talents Program. E.W. acknowledges support from the Advanced Light Source doctoral fellowship programme. G.G. and Z.X. are supported by DOE under Contract No. DE-AC02-98CH10886. J.S. and R.Z. are supported by DOE Center for Emergent Superconductivity. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract No. DE-AC02-05CH11231.

Author information

Author notes

    • Eryin Wang
    •  & Hao Ding

    These authors contributed equally to this work

Affiliations

  1. State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China

    • Eryin Wang
    • , Hao Ding
    • , Wei Yao
    • , Zhi Li
    • , Yan-Feng Lv
    • , Kun Zhao
    • , Li-Guo Zhang
    • , Shuai-Hua Ji
    • , Qi-Kun Xue
    • , Xi Chen
    •  & Shuyun Zhou
  2. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    • Eryin Wang
    •  & Alexei V. Fedorov
  3. Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

    • Zhijun Xu
    • , John Schneeloch
    • , Ruidan Zhong
    •  & Genda Gu
  4. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

    • Lili Wang
    • , Ke He
    •  & Xucun Ma
  5. Institute of Advanced Study, Tsinghua University, Beijing 100084, China

    • Hong Yao

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Contributions

S.Z. and X.C. conceived and designed the experiments. H.D., Z.L., Y-F.L., K.Z. and L-G.Z. carried out MBE growth and STM measurements with assistance from S-H.J., L.W., K.H., X.M., X.C. and Q-K.X. Z.X., J.S., R.Z. and G.G. prepared the bulk Bi2212 samples. E.W., W.Y., A.V.F. and S.Z. performed ARPES measurements and data analysis. S.Z., X.C., H.Y. and Q-K.X. prepared the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Xi Chen or Shuyun Zhou.

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DOI

https://doi.org/10.1038/nphys2744

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