Structural and magnetotransport transitions in the electron-doped Pr1-xSrxMnO3 (0.85 <= x <= 1) manganites

The exploration of the Mn4+-rich side of the Pr1-xSrxMnO3 system has allowe d the extension of the domain of the cubic perovskite, by using a two-step process, combining synthesis under Ar flow at high temperature and O-2 pres sure annealing at lower temperature. We show that these Pr-doped cubic pero vskites exhibit a coupled structural (cubic-tetragonal) and magnetic (para- antiferro) transition connected with a resistivity jump at the same tempera ture. The strong interplay between lattice, charges, and spins for these ox ides results from the appearance at low temperature of the distorted C-type antiferromagnetic structure. The Pr1-xSrxMnO3 magnetic phase diagram shows , for 0.9 less than or equal to x less than or equal to 1 (i.e., on the Mn4 +-rich side), the existence at low temperature of C- and G-type antiferroma gnetism. The absence of ferromagnetic-antiferromagnetic competition explain s that magnetoresistante properties are not observed in this system, in con trast to Mn4+-rich Ln(1-x)Ca(x)MnO(3) systems.