How the substitution of Zn for Cu destroys superconductivity in YBCO system?

Understanding the mechanism of suppression of superconductivity in perovskite cuprates is as important as to discover the cause of its evolution. Substituting Zn for Cu is known to rapidly suppress the superconductivity in these perovskites but the mechanism is still not understood. To throw some light on this, polycrystalline YBa2(Cu1−xZnx)3O7−δ samples (x = 0.0–0.06) were synthesized and investigated using X-ray diffraction, titration, resistivity, magnetization, X-ray absorption and photoemission measurements. Results show that their oxygen stoichiometry (δ) changes on Zn substitution affect their normal state resistivity as well as their Tc. However, the observed changes cannot be accounted for solely on the basis of changes in δ. Zn cation is found to act as strong scattering centre in the lattice that causes local lattice distortion (LLD). It also induces local magnetic moment as evidenced from our magnetization results. It is concluded that a combination of Δδ, LLD and magnetic pair breaking effect is responsible for the observed rapid suppression of superconductivity.