Letter | Published:

Enhanced superconductivity in surface-electron-doped iron pnictide Ba(Fe1.94Co0.06)2As2

Nature Materials volume 15, pages 12331236 (2016) | Download Citation

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Abstract

The superconducting transition temperature (TC) in a FeSe monolayer on SrTiO3 is enhanced up to 100 K (refs 1,2,3,4). High TC is also found in bulk iron chalcogenides with similar electronic structure5,6,7 to that of monolayer FeSe, which suggests that higher TC may be achieved through electron doping, pushing the Fermi surface (FS) topology towards leaving only electron pockets. Such an observation, however, has been limited to chalcogenides, and is in contrast to the iron pnictides, for which the maximum TC is achieved with both hole and electron pockets forming considerable FS nesting instability8,9,10,11. Here, we report angle-resolved photoemission characterization revealing a monotonic increase of TC from 24 to 41.5 K upon surface doping on optimally doped Ba(Fe1−xCox)2As2. The doping changes the overall FS topology towards that of chalcogenides through a rigid downward band shift. Our findings suggest that higher electron doping and concomitant changes in FS topology are favourable conditions for the superconductivity, not only for iron chalcogenides, but also for iron pnictides.

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Change history

  • 29 September 2016

    In the original version of this Letter, the x-axes in Fig. 2a-d were mislabelled; they should have read 'EEF (meV)'. This has been corrected in all versions.

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Acknowledgements

This work is supported by IBS-R009-G2, IBS-R009-G1 and the Basic Science Research Program (No. 2012-008233) funded by Korean Federation of Science and Technology Societies. This research is also supported by the Strategic International Collaborative Research Program (SICORP) from Japan Science and Technology Agency. The Advanced Light Source is supported by the Office of Basic Energy Sciences of the US DOE under Contract No. DE-AC02-05CH11231.

Author information

Affiliations

  1. Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea

    • W. S. Kyung
    •  & S. S. Huh
  2. Center for Correlated Electron Systems, Institute for Basic Science, Seoul 151-742, Republic of Korea

    • W. S. Kyung
    • , S. S. Huh
    • , K.-Y. Choi
    • , C. Kim
    •  & Y. K. Kim
  3. Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea

    • W. S. Kyung
    • , S. S. Huh
    • , K.-Y. Choi
    • , C. Kim
    •  & Y. K. Kim
  4. Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea

    • Y. Y. Koh
  5. Department of Physics, Osaka University 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan

    • M. Nakajima
  6. National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan

    • H. Eisaki
  7. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    • J. D. Denlinger
    • , S.-K. Mo
    •  & Y. K. Kim
  8. Department of Physics, KAIST, Daejon 34141, Republic of Korea

    • Y. K. Kim

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Contributions

Y.K.K. conceived the work. W.S.K. and Y.K.K. performed ARPES measurements with the support from J.D.D. and S.-K.M., and analysed the data. Samples were grown and characterized by K.-Y.C., M.N. and H.E. All authors discussed the results. Y.K.K., S.-K.M. and C.K. led the project and manuscript preparation, with contributions from all authors.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to S.-K. Mo or C. Kim or Y. K. Kim.

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DOI

https://doi.org/10.1038/nmat4728

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