Conductivity fluctuation of YBa2Cu3O7 - delta/Sr2YSbO6/SrTiO3 thin films

Mayorga, P. A.; Téllez, D.A. Landı́nez; Madueño, Q.; Alfonso, J. E.; Roa-Rojas, J.

doi:10.1590/s0103-97332006000600076

Cited by 13 publications

(4 citation statements)

References 9 publications

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“…With decreasing temperatures above but closer to T c , the fluctuation conductivity σ of both free and added samples is described by a power law critical regime with an exponent λ c around 0.3. This regime was also observed in others polycrystalline [22], single crystal [30], and thin film [31] samples. The obtained values are consistent with predictions of the 3D-XY model with the dynamics given by the model E of Hohenberg and Halperin [32,33].…”

Section: Resultssupporting

confidence: 79%

Excess Conductivity Study in Nano-CoFe2O4-Added YBa2Cu3O7−d and Y3Ba5Cu8O18±x Superconductors

Slimani

Hannachi

Salem

et al. 2015

J Supercond Nov Magn

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We report electrical conductivity fluctuation analyses on YBa 2 Cu 3 O 7−d (noted Y-123) and Y 3 Ba 5 Cu 8 O 18±x (noted Y-358) polycrystalline samples added with nano-sized ferrite cobalt (CoFe 2 O 4 ) particles. Phases and microstructure have been systematically investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results reveal that the lattice parameters change for both Y-123 and Y-358 phases. SEM observations show that the grain size is reduced with increasing the content of CoFe 2 O 4 in the yttrium-based superconductor (YBCO) matrix The temperature dependence of electrical resistivity ρ(T ) has been measured and the effect of addition of magnetic CoFe 2 O 4 in the paraconductivity region has been reported. The thermodynamic fluctuation is obtained by analyzing the excess of conductivity on the basis of the Aslamazov-Larkin theory. The coherence length, the effective layer thickness, critical magnetic fields, and critical current density are estimated. Superconducting parameters are affected by the nanoparticle addition, and results are discussed in relevance to the structural and microstructure differences between Y-123 and Y-358.

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Section: Resultssupporting

confidence: 79%

Excess Conductivity Study in Nano-CoFe2O4-Added YBa2Cu3O7−d and Y3Ba5Cu8O18±x Superconductors

Slimani

Hannachi

Salem

et al. 2015

J Supercond Nov Magn

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“…6a. This regime was also observed in others not only polycrystalline [30] but also in single crystal [42] and thin film [43] samples. The solid lines in mean-field regions represent theoretical fits with the slopes of − 0.5, − 1 and − 1.5 for 3-D, 2-D, and 1-D systems, respectively.…”

Section: Excess Conductivity Methodssupporting

confidence: 80%

Conductivity Fluctuation and Some Parameters of High temperature Superconductor Polycrystalline Y1Ba2Cu3O7−δ doped with Silver Nanoparticles

Shams

Ranjbar

2019

Braz J Phys

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In this study, we report the effect of Ag nanoparticles doping on the dimensional fluctuations of superconducting order parameters, crystal structure, and some parameters of Y 1 Ba 2 Cu 3 O 7−δ + × Ag (x = 0.0, 0.06, 0.1, 0.3, and 0.6 wt%) polycrystalline ceramics. By increasing the content of Ag in YBCO matrix, X-ray diffraction (XRD) with the Rietveld refinement technique revealed that the crystal lattice parameters changed and the orthorhombicity decreased slightly. Also, the increase of Ag wt% caused a decrease of superconducting transition temperatures (Tc) which are determined from the standard four-probe method and dropped abruptly. Aslamazov-Larkin (AL) model was used to analyze excess conductivity fluctuation. Lawerence-Doniach (LD) temperature named T LD which is responsible for the dimensional nature of fluctuation inside the grains is influenced by nano-silver combination in the compound. Crossover temperature from 2D to 3D (T LD) decreased in the mean-field region as a resultant dominance of 3D region by increasing of Ag in YBCO matrix. The decrease in zero-resistance critical temperature (T c zero), zero-temperature coherence length along the c-axis ξ c (0), and super layer length d values implies the degradation of inter-grain weak links, more disorder state of samples and unsettling of the mean free path for the charge carriers respectively with addition of silver nanoparticles. The calculations based on AL and LD model showed the highest anisotropy (γ = 1.34681) for the x = 0.6 sample. The size of the Ag ions, being larger compared to Cu ions, and the number of substitution sites affects the coupling between the CuO2 planes and that results in higher anisotropy. Critical magnetic fields B c1 (0), B c2 (0), and critical current density J c (0) were indirectly calculated from the Ginzburg-Landau (GL) number and GL equations. By increasing the doping level of silver nanoparticle, these parameters were found to be higher in Ag-added YBCO samples compared to the pure Y123, meaning better intrinsic flux pinning properties of doped Y123. The silver nanoparticle inclusion reduces the grain size and increases the strength and hardness of the parent compound.

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“…Now, we can discuss the various fittings made to the graphs. In the vicinity near the mean-field temperature, the fluctuation conductivity can be described by a power-law critical regime with an exponent around 0.3 at 0, 1, and 3 T. The critical regime was also noticed in other YBCO single crystal [37], thin-film [38], and polycrystalline [39] samples. The obtained values are consistent with predictions of the 3D-XY model [40,41].…”

Section: Excess Conductivitymentioning

confidence: 67%

Excess Conductivity Analysis of an YBCO Foam Strut and Its Microstructure

Slimani,

Hannachi,

Koblischka-Veneva

et al. 2024

Materials

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Struts of a superconducting YBa2Cu3Oy (YBCO) foam prepared by the infiltration growth method on the base of commercial polyurethane foams were extracted from the bulk, and thoroughly characterized concerning the microstructure and the magnetoresistance, measured by the four-point technique. Optical microscopy, electron microscopy, electron backscatter diffraction and atomic force microscopy observations indicate a unique microstructure of the foam struts which shows a large amount of tiny Y2BaCuO5 (Y-211) particles (with diameters between 50 and 100 nm) being enclosed in channel-like grain boundaries between the YBCO grains and a one-of-a-kind surface of the struts covered with Ba3Cu5Oy-particles. The resistance data obtained at temperatures in the range 4.2 K ≤T≤ 150 K (applied magnetic fields ranging from 0 to 7 T) were analyzed in the framework of the fluctuation-induced conductivity (FIC) approach using the models of Aslamazov–Larkin (AL) and Lawrence–Doniach (LD). The resulting FIC curves reveal the presence of five distinct fluctuation regimes, namely, the short-wave (SWF), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and critical (CR) fluctuation domains. The analysis of the FIC data enable the coherence length in the direction of the c-axis at zero-temperature (ξc(0)), the irreversibility field (Birr), the upper critical magnetic field (Bc2), the critical current density at T= 0 K (Jc(0)) and several other parameters describing the the material’s superconducting properties to be determined. The present data reveal that the minuscule Y-211 particles found along the YBCO grain boundaries alter the excess conductivity and the fluctuation behavior as compared to conventional YBCO samples, leading to a quite high value for Jc(0) for a sample with a non-optimized pinning landscape.

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Conductivity fluctuation of YBa2Cu3O7 - delta/Sr2YSbO6/SrTiO3 thin films

Cited by 13 publications

References 9 publications

Excess Conductivity Study in Nano-CoFe2O4-Added YBa2Cu3O7−d and Y3Ba5Cu8O18±x Superconductors

Excess Conductivity Study in Nano-CoFe2O4-Added YBa2Cu3O7−d and Y3Ba5Cu8O18±x Superconductors

Conductivity Fluctuation and Some Parameters of High temperature Superconductor Polycrystalline Y1Ba2Cu3O7−δ doped with Silver Nanoparticles

Excess Conductivity Analysis of an YBCO Foam Strut and Its Microstructure

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