Role of oxygen in the electron-doped superconducting cuprates

We report on resistivity and Hall measurements in thin films of the electron-doped superconducting cuprate Pr2-xCexCuO4 +/-delta. Comparisons between x=0.17 samples subjected to either ion irradiation or oxygenation demonstrate that changing the oxygen content has two separable effects: (1) a doping effect similar to that of cerium and (2) a disorder effect. These results are consistent with prior speculations that apical oxygen removal is necessary to achieve superconductivity in this compound.