Magneto-conductivity Analysis for GdBa_2Cu_3O_(7-δ) Added with Nanosized Ferrite CoFe_2O_4

摘要

Superconducting samples of type (CoFe_2O_4)_x GdBa_2Cu_3O_(7-δ), 0.0 ≤ x ≤ 0.1 wt.%, have been prepared by the conventional solid-state reaction technique and characterized using X-ray powder diffraction (XRD) and the scanning electron microscope (SEM). XRD analysis indicates that the orthorhombic structure of Gd-123 is not affected by the nanosized ferrite CoFe_2O_4 addition, whereas the volume fraction of Gd-123 increases with x up to 0.01 wt.%. Nanosized ferrite CoFe_2O_4 has been prepared by Co-precipitation method with grain size about 8 nm. The temperature dependence of electrical resistivity has been measured in zero and 0.44 T magnetic fields. Magneto-conductivity data has been analyzed in terms of Aslamazov-Larkin (AL) and Maki-Thompson (MT) models for layered superconductors, considering the orbital contribution. The superconducting parameters such as the coherence lengths along ab plane ξ_(ab)(0) and along c-direction ξ_c(0) at 0 K, anisotropic parameter Γ and phase breaking time τ_φ at 100 K have been determined as a function of nanosized ferrite CoFe_2O_4 contents. It is found that the low nanosized CoFe_2O_4 addition contents up to x = 0.01 wt.% improves the physical properties of Gd-123, while for x > 0.01 wt.% these properties are deteriorated.