RETRACTED: Inter-layer coupling and superconductivity in Cu0.5Tl0.5-1223 samples

Abstract

Inter-CuO2 planar distances in Cu0.5Tl0.5Ba2Ca2Cu3O10−δ, Cu0.5Tl0.5(BaCa)(Ca2−xMx)Cu3O10−δ (M = Mg; x=1,2), and Cu0.5Tl0.5(BaMg)(Mg2−xMx)Cu3O10−δ (M = Be; x=1,2) superconductors were doped with Mg and Be at Ca sites. X-ray diffraction analyses revealed reductions in c-axis lengths and unit cell volumes with doping, while orthorhombic distortions increased. Resistivity measurements showed that Mg doping maintained superconductivity with zero resistivity at critical temperatures, whereas Be-doped samples exhibited semiconducting behavior, likely due to instability in forming superconducting phases. Fourier transform infrared spectroscopy revealed tempering of apical Tl–OA–Cu(2) and Cu(1)–OA–Cu(2) modes and planar CuO2 oxygen modes, attributed to enhanced orthorhombic distortions and reduced inter-CuO2 planar spacing. Excess conductivity analysis demonstrated suppressed coherence length ξc(0), Fermi velocity VF, and relaxation time τϕ in Mg-doped samples due to reduced carrier density. However, flux pinning parameters, such as Bc0, Bc1, and Jc(0), were enhanced in Mg-doped samples, indicating improved superconducting characteristics. The suppression of the Cooper pair-breaking energy further reflected reduced carrier density and dielectric constant in doped samples. AIP Publishing retracted this article on December 22, 2025, due to the publication of data without authorization and concerns about potential authorship manipulation.