Effects of cobalt nanoparticles addition in Cu0.5Tl0.5-1223 superconductor composite

Cobalt nanoparticles added Co_x/Cu_0.5Tl_0.5Ba₂Ca₂Cu₃O_10-δ superconducting composites were synthesized by solid-state reaction method and their superconducting properties were reported. The samples exhibit an orthorhombic crystal structure and the volume of the unit cell decreases with the addition of cobalt nanoparticles, indicating that Co⁺³ ion diffuses from the intergranular region into the unit cells. The suppression of the onset of superconductivity and magnitude of diamagnetism is observed in AC-susceptibility measurements showing magnetic scattering from the charged particles induced by doped Co⁺³ atoms into the unit cell. The doping of unit cells with Cobalt nanoparticles from the inter-grain regions is confirmed by a shift in the peak position and intensity of various oxygen modes in FTIR absorption measurements. Excess conductivity analysis of conductivity data has shown an increase in the coherence length along the c-axis, the Fermi velocity of the carriers, and the energy required to break the Cooper-pairs with the addition of Co nanoparticles. The observed increase in the values of these parameters is likely associated with an increase in the density of charge carriers in the conducting copper oxide planes. It is suggested to be arising from the magnetic scattering of Co⁺³ ions diffusing from inter-grain sites in the unit cell. The weak pinning is also witnessed in form of an increase in the London penetration depth and Ginzburg Landau (GL) parameter κ in Co⁺³ enriched samples.