Study of Microstructure and Local Electron Structure of Zn-Doping GdBa2Cu3O7−δ Systems Using Positron Experiment

Abstract

The Zn-doped GdBa2Cu3−xZnxO7−δ (x=0.00–0.40) superconductors have been systemically investigated by structural analysis and positron lifetime. The structural results show that the lattice parameter a and b increase slightly with increasing Zn content x, and the parameter c has a small abrupt decrease. Based on the Jahn–Teller model, we analyze the results of structural distortion. From the positron lifetime data, the local electron density ne has been calculated and the result implies a redistribution of electrons between the Cu-O chains and the CuO2 planes, resulting in the carrier localization. Furthermore, combining the results of the electronic density ne and the transition temperature Tc with Zn doping content, it suggests that the carrier localization could interfere the pairing and the “charge transfer” between Cu-O chains and the CuO2 planes and then suppresses superconductivity of the systems.