The annealing process and its relationship to superconductivity in the electron-doped superconductors

Superconductivity in the high transition temperature superconductors can be achieved when the antiferromagnetic insulating parent compounds are doped with holes or electrons. The discovery of the electron-doped superconductors has obtained special attention because of the symmetry with doped charge carriers. The electron-doped superconductors can provide important clues in the mechanism of high temperature superconductivity by finding fundamental features seen in the hole-doped superconductors. Unlike hole-doped superconductors, the electron-doped compounds require the annealing process to achieve superconductivity. The role and effects of the annealing process on superconductivity have been one of the unresolved problems in the electron-doped superconductors. To investigate how the annealing process is associated to superconductivity, we performed X-ray measurement on an as-grown, an annealed superconducting, an oxygenated nonsuperconducting, and a reannealed Pr0.88LaCe0.12CuO4 samples.