Observation of an isotropic superconducting gap at the Brillouin zone center of Tl$_{0.63}$K$_{0.37}$Fe$_{1.78}$Se$_2$

X. -P. Wang; P. Richard; A. van 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

paper

Observation of an isotropic superconducting gap at the Brillouin zone center of Tl $_{0.63}$ K $_{0.37}$ Fe $_{1.78}$ Se $_{2}$

arXiv:1205.0996 · doi:10.1209/0295-5075/99/67001

Abstract

We performed a high-resolution angle-resolved photoemission spectroscopy study on superconducting (SC) Tl $_{0.63}$ K $_{0.37}$ Fe $_{1.78}$ Se $_{2}$ ( $T_{c} = 29$ K) in the whole Brillouin zone (BZ). In addition to a nearly isotropic $\sim$ 8.2 meV 2-dimensional (2D) SC gap ( $2Δ/ k_{B} T_{c} \sim 7$ ) on quasi-2D electron Fermi surfaces (FSs) located around M $(π, 0, 0)$ -A $(π, 0, π)$ , we observe a $\sim 6.2$ meV isotropic SC gap ( $2Δ/ k_{B} T_{c} \sim 5$ ) on the Z-centered 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-next neighbor exchange interaction in the ferrochalcogenide superconductors.

arXiv comment5 pages, 4 figures

Observation of an isotropic superconducting gap at the Brillouin zone center of Tl $_{0.63}$ K $_{0.37}$ Fe $_{1.78}$ Se $_{2}$

Abstract

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Observation of an isotropic superconducting gap at the Brillouin zone center of Tl0.63​K0.37​Fe1.78​Se2​

Abstract

References in corpus (20)

Cited by in corpus (26)

Observation of an isotropic superconducting gap at the Brillouin zone center of Tl $_{0.63}$ K $_{0.37}$ Fe $_{1.78}$ Se $_{2}$