Role of improving the physical properties of Sm-123 phase by adding nano-magnetic MnFe₂O₄

Superconducting samples of SmBa₂Cu₃O_7−δ (Sm-123) added with various amounts of nanosized MnFe₂O₄ addition (0.0−0.20 wt%) were investigated. The investigated samples prepared by the solid-state reaction method. The phase formation and microstructure of these samples were examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), proton induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS). XRD data indicate that the volume fraction of Sm-123 increases as nanosized MnFe₂O₄ increases up to 0.02 wt%. The elemental distribution and oxygen content were deduced from PIXE and RBS. The oxygen content slightly decreases as MnFe₂O₄ wt% increases. The superconducting transition temperature (T_c) and critical current density (J_c) of the prepared samples were estimated from electrical resistivity and transport critical current density measurements. It was found that T_c decreases as nanosized MnFe₂O₄ addition increases, while J_c enhances up to 0.02 wt%. Moreover, the temperature dependence of normal state electrical resistivity was studied in view of the pseudogap opening in order to determine the pseudogap temperature T* as a function of nanosized MnFe₂O₄ addition. T* increases as nanosized MnFe₂O₄ increased, indicating the enhancement of the pseudogap formation in HTSCs by adding magnetic impurities. The crossover to fluctuation conductivity near the T_c is discussed. - Highlights: • Nanosized MnFe₂O₄ most likely does not enter the Sm-123 crystal structure. • Samples present a metallic-like behavior in the normal state at high temperature. • Nanosized MnFe₂O₄ lead to enhancement the formation of pseudogap in cuprates HTSCs. • The increase in T_LD crossover temperature up to x=0.02 wt% has been observed. • Nanosized MnFe₂O₄ can effectively enhance the J_c of Sm-123 up to x=0.02 wt%.