Influence of Co, Ni and Zn substitution for Cu on the structural and superconducting properties of (Hg0.7Cr0.3)Sr2CuO4+δ Original Research Article

The effect of Co, Ni and Zn substitutions for Cu on the phase stability and superconducting properties of (Hg0.7Cr0.3)Sr2CuO4+δ was investigated. X-ray diffraction (XRD) revealed that both Co and Zn are soluble in the (Hg0.7Cr0.3)Sr2CuO4+δ material up to about 5% of the Cu content, whereas the solubility of Ni is extended up to 10%. Electrical resistivity and magnetic susceptibility measurements show that the value of the superconducting critical temperature Tc decreases linearly with the impurity content. The depression of Tc indicates that the suppression of the superconductivity in Co- and Ni-substituted samples is much stronger than that in Zn-substituted ones. The residual resistivity scales linearly with the doping level as expected from the impurity scattering due to disorder. Some possible explanations for the stronger suppression of Tc by the Co and Ni substitution than by Zn substitution are provided.