We compare the structure of the superconducting order parameter of overdoped BaFe1.88Ni0.12As2 and underdoped BaFe1.92Ni0.08As2 pnictides with similar \({{T}_{c}} \approx 18.0{-} 18.3\) K. Using incoherent multiple Andreev reflection effect spectroscopy, we directly determined the magnitudes of the two microscopic superconducting order parameters: the small superconducting gap and probably anisotropic large gap, their characteristic ratios and temperature dependences. We discuss similarity and difference in the gap structure, as well as possible influence of antiferromagnetic phase to superconducting properties.
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ACKNOWLEDGMENTS
We thank M.M. Korshunov, Yu.A. Aleschenko, and V.M. Pudalov for fruitful discussions. The measurements were partly performed using the equipment of the Shared Facility Center, Lebedev Physical Institute.
Funding
The work was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. 0023-2019-0005 “Physics of High-Temperature Superconductors and New Quantum Materials”).
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Kuzmicheva, T.E., Kuzmichev, S.A., Pervakov, K.S. et al. Comparison of the Gap Structure of Underdoped and Overdoped Superconducting Pnictides BaFe2 – xNixAs2. Jetp Lett. 118, 514–519 (2023). https://doi.org/10.1134/S0021364023602750
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DOI: https://doi.org/10.1134/S0021364023602750