Dopant clustering, electronic inhomogeneity, and vortex pinning in iron-based superconductors

Can-Li Song, Yi Yin, Martin Zech, Tess Williams, Michael M. Yee, Gen-Fu Chen, Jian-Lin Luo, Nan-Lin Wang, E. W. Hudson, and Jennifer E. Hoffman
Phys. Rev. B 87, 214519 – Published 27 June 2013
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We use scanning tunneling microscopy to map the surface structure, nanoscale electronic inhomogeneity, and vitreous vortex phase in the hole-doped superconductor Sr0.75K0.25Fe2As2 with Tc=32 K. We find that the low-T cleaved surface is dominated by a half Sr/K termination with 1×2 ordering and ubiquitous superconducting gap, while patches of gapless, unreconstructed As termination appear rarely. The superconducting gap varies by σ/Δ¯=16% on a 3 nm length scale, with average 2Δ¯/kBTc=3.6 in the weak-coupling limit. The vortex core size provides a measure of the superconducting coherence length ξ=2.3 nm. We quantify the vortex lattice correlation length at 9 T in comparison to several iron-based superconductors. The comparison leads us to suggest the importance of dopant size mismatch as a cause of dopant clustering, electronic inhomogeneity, and strong vortex pinning.

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  • Received 11 December 2012


©2013 American Physical Society

Authors & Affiliations

Can-Li Song1, Yi Yin1,2, Martin Zech1, Tess Williams1, Michael M. Yee1, Gen-Fu Chen3, Jian-Lin Luo3, Nan-Lin Wang3, E. W. Hudson4, and Jennifer E. Hoffman1,*

  • 1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
  • 2Physics Department, Zhejiang University, Hangzhou 310027, China
  • 3Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 4Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

  • *

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Vol. 87, Iss. 21 — 1 June 2013

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