The Magnetotransport Properties and a Neutron Diffraction Study of Sr 2– x Nd x FeMoO 6 Double Perovskites

New electron-doped derivatives of the Sr2FeMoO6 double perovskite have been studied. We report on the synthesis of the Sr2–xNdxFeMoO6 (x = 0, 0.2, 0.4 and 0.6) perovskite series by a wet chemistry procedure and its characterization. The evolution of the crystal and magnetic structure has been analyzed from neutron powder diffraction data. The partial replacement of Sr2+ cations by higher valence Nd3+ cations induces an injection of electrons into the Fe/Mo sublattice. A bond-valence study demonstrates that this electron-injection preferentially affects the Mo orbitals. This substitution leads to a distortion of the structure from tetragonal (I4/m) to monoclinic (P21/n) at room temperature for x ≥ 0.4 and an increase of the disorder between Fe and Mo cations. This effect has severe consequences for the magnetic properties, notably a reduction of the saturation magnetization and a non-monotonic behavior of the Curie temperature. Magnetotransport measurements show a significant increment of the magnetoresistance at low temperature for high values of x. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)