The \({\text{Cu}}_{0.5}{\text{Tl}}_{0.5}{\text{Ba}}_{2}{\text{Ca}}_{2}{\text{Cu}}_{3}{\text{O}}_{10-\delta }\) (CuTl-1223) superconductors are well known for their high superconducting transition temperature and remarkable critical current density. The superconducting properties of CuTl-1223 are strongly influenced by the charge carrier concentration and spin interactions in the copper oxide planes. In this study, we have synthesized \(Cu_{0.5 - y} K_{y} Tl_{0.5} Ba_{2} Ca_{2} (Cu_{3 - x} Ni_{x} O_{10 - \delta } )\) superconductors with (x = 0, 0.5, 1.0, and 1.5 and y = 0, 0.25 wt%) to investigate the role of spin in the mechanism of superconductivity. The synthesized materials were characterized by X-ray diffraction (XRD), four-probe resistivity, FTIR absorption, and excess conductivity measurements to assess the impact of Ni and K doping on their superconducting behavior. Potassium doping, which lacks spin, resulted in the suppression of superconductivity highlighting the crucial role of copper spins in the material’s performance. Ni doping, which introduces a magnetic moment, disrupts the antiferromagnetic alignment of copper spins, leading to a reduction in superconductivity. Individual doping with either K or Ni results in a reduction of critical temperature (Tc, (ρ=0)),while the coexistence of K and Ni has been observed to promote Cooper-pair formation and enhance Tc(ρ=0) in these superconductors. Our results demonstrate the critical contribution of copper spins and highlight the interplay between carrier density and magnetic interactions in optimizing the performance of high-temperature cuprate superconductors.
