d-Hole localization and the suppression of superconductivity in YBa2(Cu1-xZnx)3O7-y

The temperature and Zn concentration dependence of the electrical resistivity, specific heat, magnetic susceptibility, and electron paramagnetic resonance (EPR) spectra of YBa2(Cu1-xZnx)3O7-y with y∼0.1 has been measured for x≤0.16. In addition, the temperature and field dependence of the magnetization has been measured for 2<T<300K and 0<H<9.0T, along with the temperature and quasihydrostatic pressure dependence of the electrical resistivity for selected samples for 0<P<13 GPa. The substitution of Zn for Cu in YBa2Cu3O7-y causes a rapid and nearly linear depression of the superconducting transition temperature, Tc, with Tc going to 0 K for x≥ 0.10. YBa2(Cu1-xZnx)3O7-y retains the YBa2Cu3O7-y orthorhombic structure for x≤0.16 for both the superconducting and nonsuperconducting samples. Initially, the unit cell volume increases nearly linearly with Zn content; however, an abrupt change occurs in the vicinity x=0.8-0.10. For x<0.10, the temperature dependence of the electrical resistivity, ρ(T), is metallic-like (d ρ/d T>0) and ρ increases gradually with increasing Zn content. However, for x≥ 0.10, ρ(T) becomes semiconductor-like, with a very rapid increase of the resistivity with increasing x. The electrical resistivity, magnetic susceptibility, EPR spectra, and specific heat all indicate that the d-holes associated with the Cu ions become localized in the nonsuperconducting phase, x>-0.10. © 1988 Plenum Publishing Corporation.