Observation of an isotropic superconducting gap at the Brillouin zone centre of Tl 0.63K 0.37Fe 1.78Se 2

X. P. Wang; P. Richard; X. Shi; A. Roekeghem; Y. B. Huang; E. Razzoli; T. Qian; E. Rienks; S. Thirupathaiah; H. D. Wang; C. H. Dong; M. H. Fang; M. Shi; H. Ding

doi:10.1209/0295-5075/99/67001

Observation of an isotropic superconducting gap at the Brillouin zone centre of Tl _0.63K _0.37Fe _1.78Se ₂

X. P. Wang^*, P. Richard, X. Shi, A. Roekeghem, Y. B. Huang, E. Razzoli, T. Qian, E. Rienks, S. Thirupathaiah, H. D. Wang, C. H. Dong, M. H. Fang, M. Shi, H. Ding

^*Corresponding author for this work

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

34 Citations (Scopus)

Abstract

We performed a high-resolution angle-resolved photoemission spectroscopy study on superconducting (SC) Tl _0.63K _0.37Fe _1.78Se ₂ (T _c=29K) in the whole Brillouin zone (BZ). In addition to a nearly isotropic 8.2meV 2-dimensional (2D) SC gap (2Δ/k _BT _c7) on quasi-2D electron Fermi surfaces (FSs) located around M(π,0,0)-A(π,0,π), we observe a 6.2meV isotropic SC gap (2Δ/k _BT _c5) on the Z-centred electron FS that rules out any d-wave pairing symmetry and rather favors an s-wave symmetry. All isotropic SC gap amplitudes can be fit by a single-gap function derived from a local strong-coupling approach suggesting an enhancement of the next-nearest neighbor exchange interaction in the ferrochalcogenide superconductors.

Original language	English
Article number	67001
Journal	EPL
Volume	99
Issue number	6
DOIs	https://doi.org/10.1209/0295-5075/99/67001
Publication status	Published - Sept 2012
Externally published	Yes

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@article{92ebfc994f7744498a18c7c40bfa391a,

title = "Observation of an isotropic superconducting gap at the Brillouin zone centre of Tl 0.63K 0.37Fe 1.78Se 2",

abstract = "We performed a high-resolution angle-resolved photoemission spectroscopy study on superconducting (SC) Tl 0.63K 0.37Fe 1.78Se 2 (T c=29K) in the whole Brillouin zone (BZ). In addition to a nearly isotropic 8.2meV 2-dimensional (2D) SC gap (2Δ/k BT c7) on quasi-2D electron Fermi surfaces (FSs) located around M(π,0,0)-A(π,0,π), we observe a 6.2meV isotropic SC gap (2Δ/k BT c5) on the Z-centred electron FS that rules out any d-wave pairing symmetry and rather favors an s-wave symmetry. All isotropic SC gap amplitudes can be fit by a single-gap function derived from a local strong-coupling approach suggesting an enhancement of the next-nearest neighbor exchange interaction in the ferrochalcogenide superconductors.",

author = "Wang, {X. P.} and P. Richard and X. Shi and A. Roekeghem and Huang, {Y. B.} and E. Razzoli and T. Qian and E. Rienks and S. Thirupathaiah and Wang, {H. D.} and Dong, {C. H.} and Fang, {M. H.} and M. Shi and H. Ding",

year = "2012",

month = sep,

doi = "10.1209/0295-5075/99/67001",

language = "English",

volume = "99",

journal = "EPL",

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T1 - Observation of an isotropic superconducting gap at the Brillouin zone centre of Tl 0.63K 0.37Fe 1.78Se 2

AU - Wang, X. P.

AU - Richard, P.

AU - Shi, X.

AU - Roekeghem, A.

AU - Huang, Y. B.

AU - Razzoli, E.

AU - Qian, T.

AU - Rienks, E.

AU - Thirupathaiah, S.

AU - Wang, H. D.

AU - Dong, C. H.

AU - Fang, M. H.

AU - Shi, M.

AU - Ding, H.

PY - 2012/9

Y1 - 2012/9

N2 - We performed a high-resolution angle-resolved photoemission spectroscopy study on superconducting (SC) Tl 0.63K 0.37Fe 1.78Se 2 (T c=29K) in the whole Brillouin zone (BZ). In addition to a nearly isotropic 8.2meV 2-dimensional (2D) SC gap (2Δ/k BT c7) on quasi-2D electron Fermi surfaces (FSs) located around M(π,0,0)-A(π,0,π), we observe a 6.2meV isotropic SC gap (2Δ/k BT c5) on the Z-centred electron FS that rules out any d-wave pairing symmetry and rather favors an s-wave symmetry. All isotropic SC gap amplitudes can be fit by a single-gap function derived from a local strong-coupling approach suggesting an enhancement of the next-nearest neighbor exchange interaction in the ferrochalcogenide superconductors.

AB - We performed a high-resolution angle-resolved photoemission spectroscopy study on superconducting (SC) Tl 0.63K 0.37Fe 1.78Se 2 (T c=29K) in the whole Brillouin zone (BZ). In addition to a nearly isotropic 8.2meV 2-dimensional (2D) SC gap (2Δ/k BT c7) on quasi-2D electron Fermi surfaces (FSs) located around M(π,0,0)-A(π,0,π), we observe a 6.2meV isotropic SC gap (2Δ/k BT c5) on the Z-centred electron FS that rules out any d-wave pairing symmetry and rather favors an s-wave symmetry. All isotropic SC gap amplitudes can be fit by a single-gap function derived from a local strong-coupling approach suggesting an enhancement of the next-nearest neighbor exchange interaction in the ferrochalcogenide superconductors.

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DO - 10.1209/0295-5075/99/67001

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SN - 0295-5075

VL - 99

JO - EPL

JF - EPL

IS - 6

M1 - 67001

ER -

Observation of an isotropic superconducting gap at the Brillouin zone centre of Tl _0.63K _0.37Fe _1.78Se ₂

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