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Morgun L, Kuzmichev S, Morozov I, Degtyarenko A, Sadakov A, Shilov A, Zhuvagin I, Rakhmanov Y, Kuzmicheva T. Upper Critical Field and Tunneling Spectroscopy of Underdoped Na(Fe,Co)As Single Crystals. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6421. [PMID: 37834557 PMCID: PMC10573126 DOI: 10.3390/ma16196421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/15/2023]
Abstract
A comprehensive study of superconducting properties of underdoped NaFe0.979Co0.021As single crystals by a combination of upper critical field measurements and incoherent multiple Andreev reflection effect (IMARE) spectroscopy is presented. The Hc2(T) temperature dependences are measured at magnetic fields up to 16 T with in-plane and out-of-plane field directions and considered within single-band and two-band models in order to estimate the Hc2(0) value. In IMARE spectroscopy probes, the magnitude, characteristic ratio, and temperature dependence of the superconducting order parameters (ΔL,S(T)) are determined locally and directly. A possible k-space anisotropy of the large superconducting gap is demonstrated. We show that usage of a quadruple of λij0 coupling constants obtained in the IMARE experiment can significantly reduce the number of free parameters required to fit the Hc2(T) dependence within a two-band approach (from six to two).
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Affiliation(s)
- Leonid Morgun
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
| | - Svetoslav Kuzmichev
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Igor Morozov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Alena Degtyarenko
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
| | - Andrey Sadakov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
| | - Andrey Shilov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
| | - Ilya Zhuvagin
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
| | - Yevgeny Rakhmanov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Tatiana Kuzmicheva
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia; (L.M.); (S.K.)
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Llovo IF, Carballeira C, Sóñora D, Pereiro A, Ponte JJ, Salem-Sugui S, Sefat AS, Mosqueira J. Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors. Sci Rep 2021; 11:11526. [PMID: 34075106 PMCID: PMC8169784 DOI: 10.1038/s41598-021-90858-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/13/2021] [Indexed: 11/09/2022] Open
Abstract
Detailed measurements of the in-plane resistivity were performed in a high-quality Ba([Formula: see text])[Formula: see text] ([Formula: see text]) single crystal, in magnetic fields up to 9 T and with different orientations [Formula: see text] relative to the crystal c axis. A significant [Formula: see text] rounding is observed just above the superconducting critical temperature [Formula: see text] due to Cooper pairs created by superconducting fluctuations. These data are analyzed in terms of a generalization of the Aslamazov-Larkin approach, that extends its applicability to high reduced-temperatures and magnetic fields. This method allows us to carry out a criterion-independent determination of the angular dependence of the upper critical field, [Formula: see text]. In spite of the relatively small anisotropy of this compound, it is found that [Formula: see text] presents a significant deviation from the single-band 3D anisotropic Ginzburg-Landau (3D-aGL) approach, particularly for large [Formula: see text] (typically above [Formula: see text]). These results are interpreted in terms of the multiband nature of these materials, in contrast with other proposals for similar [Formula: see text] anomalies. Our results are also consistent with an effective anisotropy factor almost temperature independent near [Formula: see text], a result that differs from the ones obtained by using a single-band model.
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Affiliation(s)
- I F Llovo
- QMatterPhotonics Research Group, Departamento de Física de Partículas, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - C Carballeira
- QMatterPhotonics Research Group, Departamento de Física de Partículas, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - D Sóñora
- QMatterPhotonics Research Group, Departamento de Física de Partículas, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - A Pereiro
- QMatterPhotonics Research Group, Departamento de Física de Partículas, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - J J Ponte
- Unidade de Magnetosusceptibilidade, RIAIDT, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - S Salem-Sugui
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-972, Brazil
| | - A S Sefat
- Oak Ridge National Laboratory, Oak Ridge, TN, 87831, USA
| | - J Mosqueira
- QMatterPhotonics Research Group, Departamento de Física de Partículas, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain.
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