Studies of static magnetic order in electron-superconductors and their parent compounds

UNTIL recently, all known high- Tc superconductors involved conduction by holes; the doping of holes into the parent compound, for example by the substitution of Sr2+ or Ba2+ for La3+ in La2CuO4–y, results in a metallic state whose electronic ground state is superconducting. Recently, Tokura et al1 have discovered a series of superconducting copper oxides of general formula Ln2–xCexCuO4–y (where Ln represents Pr, Nd, Sm), with transition …