X-ray diffraction plot of BSCCO/BFO composite. The plots are slightly off-shifted for better clarity. The peaks marked up arrow ↑ represents 2201 phase and those marked down arrow ↓ represents BiFeO3 phase. Some extra peaks in composite samples marked (*) is observed which resembles with Bi free superconducting phase Ca7Sr7Cu24O41 (JCPDS: 48-1503).
Temperature variation of normalized resistivity ρ/ρ273 for BSCCO and its composites with BFO (1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, and 30%). The two arrows show the variation of Tc-on with increasing BFO concentration in the sample. The inset shows the temperature dependence of normalized resistivity (ρ/ρ273) of BFO in the sample. This resistivity is found to obey the power law . .
Plot of on-set transition temperature Tc-on and mean field transition temperature Tc1, obtained from the dR/dT plot, as a function of increasing BFO content in the sample. The lines are just a guide to eye.
Plot of as a function of temperature. Deviation from the flat behavior marks the onset of pseudogap temperature T* (shown as arrow mark). The respective plots are off-shifted for better clarity.
ρ-T plot is found to be good fit with up to 10% BSCCO/BFO. The solid lines are the fit corresponding to the equation.
For 15% BFO, temperature dependence of resistivity is fitted with and for 20%–30% BFO composite samples. The solid lines are the fit to the respective equations.
ln (Δσ) vs. ln (ε) plot of BSCCO and its composites (a) 1%, 2%, 3%, 4% (b) 5%, 10%, 15%, and 20% added BFO. 2D and 3D fitted regions are shown by straight lines along with cross over temperature at the intersection of solid lines.
Variation of critical current density (Jc) as a function of temperature (T). The solid red lines are fit to the equation in the respective regions. Plot of Jc(0), obtained from the fitting of above equation in region 2, as a function of BFO content in BSCCO is shown in the last figure. Here, the solid black line is just a guide to eye.
Schematic grain/grain boundary arrangement for BSCCO/BFO composites. The inner most circles are the superconducting grains and second one with light shade are the intrinsic grain boundaries. The additional grain boundary due to BFO (shown with dark shade circle) is present in second figure. The dark spots in the second figure stand for the BFO nano particles inside the grains acting as pinning centers.
Variation of superconducting parameters with BFO wt. %. Samples having BFO% more than 15, did not show zero resistance, hence not included here.
Various parameters obtained from the paraconductivity studies of BSCCO/BFO composites: 2D-3D cross-over temperature T0, 3D and 2D exponents λ3D and λ2D or λpercolative, Coherence length (ξ) and Josephson coupling constant (EJ). 20% sample is not included here as the TC2 is not available.
Values of critical current density Jc(0) and “n” in the two regions.
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