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 'E – EF (meV)'. This has been corrected in all versions.
References
Wang, Q. Y. et al. Interface-induced high-temperature superconductivity in single unit-cell FeSe films on SrTiO3 . Chin. Phys. Lett. 29, 037402 (2012).
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).
Tan, S. Y. et al. Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films. Nat. Mater. 12, 634–640 (2013).
Ge, J.-F. et al. Superconductivity above 100 K in single-layer FeSe films on doped SrTiO3 . Nat. Mater. 14, 285–289 (2015).
Zhang, Y. et al. Nodeless superconducting gap in AxFe2Se2 (A = K, Cs) revealed by angle-resolved photoemission spectroscopy. Nat. Mater. 10, 273–277 (2011).
Chang, C. C. et al. Superconductivity in Fe-chalcogenides. Physica C 514, 423–434 (2015).
Niu, X. H. et al. Surface electronic structure and isotropic superconducting gap in (Li0.8Fe0.2)OHFeSe. Phys. Rev. B 92, 060504(R) (2015).
Ding, H. et al. Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2 . Europhys. Lett. 83, 47001 (2008).
Terashima, K. et al. Fermi surface nesting induced strong pairing in iron-based superconductors. Proc. Natl Acad. Sci. USA 106, 7330–7333 (2009).
Hajiri, T. et al. Three-dimensional electronic structure and interband nesting in the stoichiometric superconductor LiFeAs. Phys. Rev. B 85, 094509 (2012).
Sen, S. & Ghosh, H. Fermiology of 122 family of Fe-based superconductors: an ab initio study. Phys. Lett. A 379, 843–847 (2015).
Kamihara, Y. et al. Iron-based layered superconductor La[O1−xFx]FeAs (x = 0.05, 0.12) with Tc = 26 K. J. Am. Chem. Soc. 130, 3296–3297 (2008).
de la Cruz, C. et al. Magnetic order close to superconductivity in the iron-based layered LaO1−xFxFeAs systems. Nature 453, 899–902 (2008).
Miyata, Y., Nakayama, K., Sugawara, K., Sata, T. & Takahashi, T. High-temperature superconductivity in potassium-coated multilayer FeSe thin films. Nat. Mater. 14, 775–779 (2015).
Tan, S. et al. Interface-induced superconductivity and strain-dependent spin density waves in FeSe/SrTiO3 thin films. Nat. Mater. 12, 634–640 (2013).
Seo, J. J. et al. Superconductivity below 20 K in heavily electon-doped surface layer of FeSe bulk crystal. Nat. Commun. 7, 11116 (2016).
Ye, Z. R. et al. Simultaneous emergence of superconductivity, inter-pocket scattering and nematic fluctuation in potassium-coated FeSe superconductor. Preprint at http://arXiv.org/abs/1512.02526 (2015).
Lee, C.-H. et al. Effect of structural parameters on superconductivity in fluorine-free LnFeAsO1−y (Ln = La, Nd). J. Phys. Soc. Jpn 77, 083704 (2008).
Zhang, C. et al. Effect of pnictogen height on spin waves in iron pnictide. Phys. Rev. Lett. 112, 217202 (2014).
Drotziger, S. et al. Pressure versus concentration tuning of the superconductivity in Ba(Fe1−xCox)2As2 . J. Phys. Soc. Jpn 79, 124705 (2010).
Ohta, T., Bostwick, A., Seyller, T., Horn, K. & Rotenberg, E. Controlling the electronic structure of bilayer graphene. Science 313, 951–954 (2006).
Hossain, M. et al. In situ doping control of the surface of high-temperature superconductors. Nat. Phys. 4, 527–531 (2008).
Zhang, Y. et al. Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2 . Nat. Nanotech. 9, 111–115 (2014).
Nakajima, M. et al. Evolution of the optical spectrum with doping in Ba(Fe1−xCox)2As2 . Phys. Rev. B 81, 104528 (2010).
Kim, Y. K. et al. Electronic structure of detwinned BaFe2As2 from photoemission and first principles. Phys. Rev. B 83, 063509 (2011).
Usui, H. & Kuroki, K. Maximizing the Fermi-surface multiplicity optimizes the superconducting state of iron pnictide compounds. Phys. Rev. B 84, 024505 (2011).
Dynes, R. C., Narayanamurti, V. & Garno, J. P. Direct measurement of quasiparticle-lifetime broadening in a strong-coupled superconductor. Phys. Rev. Lett. 41, 1509–1512 (1978).
Bardeen, J., Cooper, L. N. & Schrieffer, J. R. Microscopic theory of superconductivity. Phys. Rev. 106, 162–164 (1957).
Norman, M. R., Randeria, M., Ding, H. & Campuzano, J. C. Phenomenology of the low-energy spectral function in high-Tc superconductors. Phys. Rev. B 57, R11093 (1998).
Thaler, A. et al. Physical and magnetic properties of Ba(Fe1−xRux)2As2 single crystals. Phys. Rev. B 82, 014534 (2010).
Rotter, M., Langerl, M., Tegel, M. & Johrendt, D. Superconductivity and crystal structures of (Ba1−xKx)Fe2As2 (x = 0 − 1). Angew. Chem. Int. Ed. 47, 7949–7952 (2008).
Onari, S. & Kontani, H. Violation of Anderson’s theorem for the sign-reversing s-wave state of iron-pnictide superconductors. Phys. Rev. Lett. 103, 177001 (2009).
Shen, D. W. et al. Novel mechanism of a charge density wave in a transition metal dichalcogenide. Phys. Rev. Lett. 114, 167001 (2015).
Paglione, J. & Greene, R. High temperature superconductivity in iron-based materials. Nat. Phys. 6, 645–658 (2010).
Chen, X., Maiti, S., Linscheid, A. & Hirschfeld, P. J. Electron pairing in the presence of incipient bands in iron-based superconductors. Phys. Rev. B 92, 224514 (2015).
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.
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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.
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Kyung, W., Huh, S., Koh, Y. et al. Enhanced superconductivity in surface-electron-doped iron pnictide Ba(Fe1.94Co0.06)2As2. Nature Mater 15, 1233–1236 (2016). https://doi.org/10.1038/nmat4728
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DOI: https://doi.org/10.1038/nmat4728
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