Superconductivity and magnetism of La2Cu1−xZnxO4+δ chemically oxidized by NaClO

The structural, superconducting and magnetic properties of La2Cu1−xZnxO4+δ (0≤x≤0.1) chemically oxidized by NaClO at room temperature were studied. All the samples before and after oxidation are single phase with orthorhombic structure, as indicated by their powder X-ray diffraction analysis. The iodometric titration results indicate that Zn-substituted La2Cu1−xZnxO4 is more favorable for the insertion of the excess oxygen, as compared to the Zn-free La2CuO4. The Tc suppression rate resulting from Zn substitution in La2Cu1−xZnxO4+δ is −12.4 K/%. The effective magnetic moment induced by the non-magnetic Zn ion is the order of one Bohr magneton, which decreases with increasing the Zn concentrations in the range examined. The latter two results are qualitatively well consistent with those obtained in La2−xSrxCu1−yZnyO4 with the Sr optimal doping. This reveals that the non-magnetic Zn ions play the same role in both of the La2Cu1−xZnxO4+δ with the excess oxygen content of about 0.1 and the La2−xSrxCu1−yZnyO4 with the Sr optimal doping.