Anisotropy dependence of the fluctuation spectroscopy in the critical and gaussian regimes in superconducting NaFe1−xCo
                x
              As single crystals

Ahmad, Dawood; Choi, Woojae; Sóñora, D.; Oh, Yoon Seok; Mosqueira, J.; Park, Tuson; Kwon, Yong Seung

doi:10.1038/s41598-018-26939-8

Cited by 6 publications

(8 citation statements)

References 48 publications

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“…2 a–c, the measured deviates from (beyond the experimental uncertainty) when K, which corresponds to a reduced temperature around 0.3. Thus, in what follows we have set , a value that is close to the one found in other FeSC 27 – 31 . In the zero-field limit (for ), and in the absence of cutoff ( ), Eq.…”

Section: Resultssupporting

confidence: 53%

“…The conductivity induced by superconducting fluctuations (or paraconductivity) is given by where is the normal-state or background resistivity extrapolated to temperatures near . This background resistivity was determined by a linear fit to the resistivity above 35 K (i.e., above ) where fluctuation effects are expected to be negligible 27 – 31 . Some examples of this procedure for different field amplitudes and orientations are presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Nonetheless, this procedure is strongly dependent on the particular criterion used (e.g., 20%, 50% or 80% of ), as different factors round the curves near the superconducting transition temperature, . Firstly, due to the relatively high and the small value of the coherence length (just a few nm), thermal fluctuation effects near play an important role in these materials 26 , and contribute to the rounding of the resistive transition 27 – 31 . These effects are also strongly dependent on the amplitude and orientation of the applied magnetic field 32 .…”

Section: Introductionmentioning

confidence: 99%

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Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors

Llovo

Carballeira

Sóñora

et al. 2021

Sci Rep

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Detailed measurements of the in-plane resistivity were performed in a high-quality Ba($$\hbox {Fe}_{1-x}\hbox {Co}_{{x}}$$ Fe 1 - x Co x )$$_2\hbox {As}_2$$ 2 As 2 ($$x=0.065$$ x = 0.065 ) single crystal, in magnetic fields up to 9 T and with different orientations $$\theta$$ θ relative to the crystal c axis. A significant $$\rho (T)_{H,\theta }$$ ρ ( T ) H , θ rounding is observed just above the superconducting critical temperature $$T_c$$ T c 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, $$H_{c2}(\theta )$$ H c 2 ( θ ) . In spite of the relatively small anisotropy of this compound, it is found that $$H_{c2}(\theta )$$ H c 2 ( θ ) presents a significant deviation from the single-band 3D anisotropic Ginzburg-Landau (3D-aGL) approach, particularly for large $$\theta$$ θ (typically above $$\sim 60^o$$ ∼ 60 o ). These results are interpreted in terms of the multiband nature of these materials, in contrast with other proposals for similar $$H_{c2}(\theta )$$ H c 2 ( θ ) anomalies. Our results are also consistent with an effective anisotropy factor almost temperature independent near $$T_c$$ T c , a result that differs from the ones obtained by using a single-band model.

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Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors

Llovo

Carballeira

Sóñora

et al. 2021

Sci Rep

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show abstract

“…This background resistivity was determined by a linear fit to the resistivity above 35 K (i.e., above 1.5T c ) where fluctuation effects are expected to be negligible. [27][28][29][30][31] Some examples of this procedure for different field amplitudes and orientations are presented in Figs. 2a-c.…”

Section: Determination Of the Normal State Backgroundmentioning

confidence: 99%

“…Firstly, due to the relatively high T c and the small value of the coherence length (just a few nm), thermal fluctuation effects near T c (H) play an important role in these materials, 26 and contribute to the rounding of the resistive transition. [27][28][29][30][31] These effects are also strongly dependent on the amplitude and orientation of the applied magnetic field. 32 A second factor is the effect of T c inhomogeneities: These compounds are generally non-stoichiometric, and their T c depends on the doping level.…”

Section: Introductionmentioning

confidence: 99%

Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors

Llovo,

Carballeira,

Sóñora

et al. 2021

Preprint

Self Cite

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Detailed measurements of the in-plane resistivity were performed in a high-quality Ba(Fe 1−x Co x ) 2 As 2 (x = 0.065) single crystal, in magnetic fields up to 9 T and with different orientations θ relative to the crystal c axis. A significant ρ(T ) H,θ rounding is observed just above the superconducting critical temperature T c 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, H c2 (θ ). In spite of the relatively small anisotropy of this compound, it is found that H c2 (θ ) presents a significant deviation from the single-band 3D anisotropic Ginzburg-Landau (3D-aGL) approach, particularly for large θ (typically above ∼ 60 o ). These results are interpreted in terms of the multiband nature of these materials, in contrast with other proposals for similar H c2 (θ ) anomalies. Our results are also consistent with an effective anisotropy factor almost temperature independent near T c , a result that differs from the ones obtained by using a single-band model. c2 18-21 However, an anomalous behavior has been reported in some of these compounds, 22,23 qualitatively similar to the behavior observed in other two-band superconductors, such as MgB 2 . 24,25

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Fluctuation magnetoconductivity in superconducting Ca10(Pt4As8)(Fe2As2)5 single crystal

Choi

Park²,

Kwon³

2022

Results in Physics

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Anisotropy dependence of the fluctuation spectroscopy in the critical and gaussian regimes in superconducting NaFe1−xCo x As single crystals

Cited by 6 publications

References 48 publications

Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors

Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors

Multiband effects on the upper critical field angular dependence of 122-family iron pnictide superconductors

Fluctuation magnetoconductivity in superconducting Ca10(Pt4As8)(Fe2As2)5 single crystal

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