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

doi:10.1103/PhysRevX.4.031001

Observation of momentum-confined in-gap impurity state in Ba_0.6K_0.4Fe₂As₂: 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

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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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 language	English
Article number	031001
Journal	Physical Review X
Volume	4
Issue number	3
DOIs	https://doi.org/10.1103/PhysRevX.4.031001
Publication status	Published - 2014
Externally published	Yes

Keywords

Condensed matter physics
Strongly correlated materials
Superconductivity

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10.1103/PhysRevX.4.031001

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Zhang, P., Richard, P., Qian, T., Shi, X., Ma, J., Zeng, L. K., Wang, X. P., Rienks, E., Zhang, C. L., Dai, P., You, Y. Z., Weng, Z. Y., Wu, X. X., Hu, J. P., & Ding, H. (2014). Observation of momentum-confined in-gap impurity state in Ba_0.6K_0.4Fe₂As₂: Evidence for antiphase s_± pairing. Physical Review X, 4(3), Article 031001. https://doi.org/10.1103/PhysRevX.4.031001

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

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.",

keywords = "Condensed matter physics, Strongly correlated materials, Superconductivity",

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

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doi = "10.1103/PhysRevX.4.031001",

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T2 - Evidence for antiphase s± pairing

AU - Zhang, P.

AU - Richard, P.

AU - Qian, T.

AU - Shi, X.

AU - Ma, J.

AU - Zeng, L. K.

AU - Wang, X. P.

AU - Rienks, E.

AU - Zhang, C. L.

AU - Dai, Pengcheng

AU - You, Y. Z.

AU - Weng, Z. Y.

AU - Wu, X. X.

AU - Hu, J. P.

AU - Ding, H.

PY - 2014

Y1 - 2014

N2 - 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.

AB - 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.

KW - Condensed matter physics

KW - Strongly correlated materials

KW - Superconductivity

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DO - 10.1103/PhysRevX.4.031001

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VL - 4

JO - Physical Review X

JF - Physical Review X

IS - 3

M1 - 031001

ER -

Observation of momentum-confined in-gap impurity state in Ba_0.6K_0.4Fe₂As₂: Evidence for antiphase s_± pairing

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Keywords

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