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arXiv · 1109.0229

Nodal superconducting gap structure in ferropnictide superconductor BaFe2(As0.7P0.3)2

Y. Zhang·Z. R. Ye·Q. Q. Ge·F. Chen·Juan Jiang·M. Xu·B. P. Xie·D. L. Feng
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Abstract

The superconducting gap is a pivotal character for a superconductor. While the cuprates and conventional phonon-mediated superconductors are characterized by distinct d-wave and s-wave pairing symmetry with nodal and nodeless gap distribution respectively, the superconducting gap distributions in iron-based superconductors are rather diversified. While nodeless gap distributions have been directly observed in Ba1-xKxFe2As2, BaFe2-xCoxAs2, KxFe2-ySe2, and FeTe1-xSex, the signatures of nodal superconducting gap have been reported in LaOFeP, LiFeP, KFe2As2, BaFe2(As1-xPx)2, BaFe2-xRuxAs2 and FeSe. We here report the angle resolved photoemission spectroscopy (ARPES) measurements on the superconducting gap structure of BaFe2(As1-xPx)2 in the momentum space, and particularly, the first direct observation of a circular line node on the largest hole Fermi surface around the Z point at the Brillouin zone boundary. Our data rules out the d-wave pairing origin of the nodal gap, and unify both the nodaland nodeless gaps in iron pnictides under the s\pm pairing symmetry.

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Y. Zhang, Z. R. Ye, Q. Q. Ge, F. Chen, Juan Jiang, M. Xu, B. P. Xie, D. L. Feng. 2011-09-01. Nodal superconducting gap structure in ferropnictide superconductor BaFe2(As0.7P0.3)2. https://doi.org/10.1038/nphys2248

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