Hole filling and pair breaking by Pr ions in YBa_{2}Cu_{3}O_{6.95±0.02}

Abstract

Measurements of the superconducting critical temperature ${\mathrm{T}}_{\mathrm{c}}$ are reported for the (${\mathrm{Y}}_{1\mathrm{-}\mathit{x}\mathrm{-}\mathit{y}}$ ${\mathrm{Ca}}_{\mathit{y}}$)${\mathrm{Pr}}_{\mathit{x}}$ ${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ system as a function of x and y. The ${\mathit{T}}_{\mathit{c}}$ vs c curves at fixed values of x can be resolved into two contributions: (1) the counteracting effects of generation and filling of holes in the ${\mathrm{CuO}}_2$ sheets by ${\mathrm{Ca}}^{2+}$ and ${\mathrm{Pr}}^{4+}$ ions, respectively, and (2) the depairing of superconducting electrons via exchange scattering of the mobile holes in the ${\mathrm{CuO}}_2$ sheets by the Pr magnetic moments.