Observation of momentum-confined in-gap impurity state in Ba0.6K0.4Fe2As2: Evidence for antiphase s± pairing

P. Zhang, P. Richard, T. Qian, X. Shi, J. Ma, L. K. Zeng, X. P. Wang, E. Rienks, C. L. Zhang, Pengcheng Dai, Y. Z. You, Z. Y. Weng, X. X. Wu, J. P. Hu, H. Ding

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

17 Citations (Scopus)

Abstract

We report the observation by angle-resolved photoemission spectroscopy of an impurity state located inside the superconducting gap of Ba0.6K0.4Fe2As2 and vanishing above the superconducting critical temperature, for which the spectral weight is confined in momentum space near the Fermi wave-vector positions.We demonstrate, supported by theoretical simulations, that this in-gap state originates from weak scattering between bands with opposite sign of the superconducting-gap phase. This weak scattering, likely due to off-plane nonmagnetic (Ba, K) disorder, occurs mostly among neighboring Fermi surfaces, suggesting that the superconducting-gap phase changes sign within holelike (and electronlike) bands. Our results impose severe restrictions on the models promoted to explain high-temperature superconductivity in these materials.
Original languageEnglish
Article number031001
JournalPhysical Review X
Volume4
Issue number3
DOIs
Publication statusPublished - 2014
Externally publishedYes

Bibliographical note

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Research Keywords

  • Condensed matter physics
  • Strongly correlated materials
  • Superconductivity

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