Annealing Paths of Pr2CuO4 and the Resulting Electronic Phase Diagrams

   Annealing is an exigency to induce superconductivity in cuprates built up of CuO2 planes with square-planar coordinated copper, aka "electron-doped" cuprates: e.g., RE2–xCexCuO4 (RE = rare-earth elements). Our analysis revealed that the electronic phase diagram for Pr2–xCexCuO4 depends strongly on the annealing path. Even undoped Pr2CuO4 is superconducting after an elaborate 2-step annealing process [Y. Krockenberger et al., Sci. Rep. 3 (2013) 2235], which is in stark contrast with a widely accepted assumption that undoped cuprates are antiferromagnetic insulators. Note that the data points denoted by filled triangles in the figure are taken from [M. Brinkmann et al., Phys. Rev. Lett. 74 (1995) 4927]. (Page 22)