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Superconducting gap structure of slightly overdoped NaFe\(_{0.955}\)Co\(_{0.045}\)As pnictides: joint SnS-Andreev spectroscopy and specific heat study

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Abstract

We present a study of the superconducting order parameter in slightly overdoped alkali-metal-based pnictides NaFe\(_{0.955}\)Co\(_{0.045}\)As with \(T_c \approx 21\) K using a combination of incoherent multiple Andreev reflection effect (IMARE) spectroscopy of planar SnS-junctions and specific heat measurements. We observe a multiple-gap superconductivity, directly and locally determine the magnitudes \(\Delta _i(0)\), characteristic ratios \(2\Delta _i(0)/k_BT_c\), and temperature dependences \(\Delta _i(T)\) of the superconducting order parameters. Possible momentum dependence of the revealed gaps is discussed. We show that a usage of the characteristic ratios obtained in the IMARE experiment provides a qualitative fit of the extracted temperature dependence of the electronic specific heat \(C_{el}(T)/T\) within the two-band approach using only two free parameters.

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Data Availibility Statement

This manuscript has associated data in a data repository. [Authors’ comment: The data are available on request.]

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Acknowledgements

The research has been partly done using the research equipment of the Shared facility center at Lebedev Physical Institute RAS.

Funding

The work is supported by Russian Science Foundation grant number 22-72-10082.

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Authors and Affiliations

  1. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prospekt, Moscow, Russia, 119991

    Svetoslav Kuzmichev, Andrei Muratov, Sergey Gavrilkin, Andrey Shilov, Yevgeny Rakhmanov, Alena Degtyarenko & Tatiana Kuzmicheva

  2. Department of Chemistry, Lomonosov Moscow State University, Leninslie Gory, Moscow, Russia, 119991

    Svetoslav Kuzmichev, Igor Morozov & Yevgeny Rakhmanov

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  1. Svetoslav Kuzmichev
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Kuzmichev, S., Muratov, A., Gavrilkin, S. et al. Superconducting gap structure of slightly overdoped NaFe\(_{0.955}\)Co\(_{0.045}\)As pnictides: joint SnS-Andreev spectroscopy and specific heat study. Eur. Phys. J. Plus 139, 74 (2024). https://doi.org/10.1140/epjp/s13360-024-04879-9

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