Evidence against hole filling by Pr in YBa2Cu3O7

Abstract

Electron-energy-loss spectroscopy has been used to investigate the changes of the electronic structure in ${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Pr}}_{\mathit{x}}$ ${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ (0≤x≤1). The O 1s absorption edges and the low-energy-loss function indicate that Pr does not fill holes in the ${\mathrm{CuO}}_2$ planes. This suggests, by comparison with other experiments, that Pr localizes mobile holes thereby leading to the suppression of superconductivity and the metal-insulator transition.