Generic phase diagram of “electron-doped” T′ cuprates

Abstract

We investigated the generic phase diagram of the electron doped superconductor, Nd 2− x Ce x CuO 4, using films prepared by metal organic decomposition. After careful oxygen reduction treatment to remove interstitial O ap atoms, we found that the T c increases monotonically from 24 K to 29 K with decreasing x from 0.15 to 0.00, demonstrating a quite different phase diagram from the previous bulk one. The implication of our results is discussed on the basis of tremendous influence of O ap “impurities” on superconductivity and also magnetism in T′ cuprates. Then we conclude that our result represents the generic phase diagram for oxygen-stoichiometric Nd 2− x Ce x CuO 4.