Structural, magnetic and transport properties of double perovskite compounds (Sr2−3 x La2 x Ba x )FeMoO6

Abstract: The crystal structure and magnetic properties of a series of ordered double perovskite oxides (Sr2−3 x La2 x Ba x )FeMoO6 () have been investigated. X-ray powder diffraction reveals that the crystal structure of the compounds changes from a tetragonal I4/m lattice to a cubic lattice around . Though the nominal average size of the A site cation of (Sr2−3 x La2 x Ba x )FeMoO6 is designed to be almost independent of x, the refinements of the crystal structure show that the lattice constants increase with x in both the tetragonal and the cubic phase regions due to electron doping. As the x increases, the degree of cationic ordering on the B site is decreased pronouncedly, while the Curie temperature of the compounds is nearly unchanged. The saturation magnetization of the compounds decreases with x and shows a linear dependence on the degree of cation ordering. The resistivity of the parent compound shows a semiconducting behavior below room temperature, but those of the doped samples exhibit a metal–semiconductor transition. A correlation between the resistivity and metal-semiconducting transition temperature (T M−S) is observed. The resistivity and T M−S of the compounds decrease with x for and increase for . Magnetoresistance of the compounds is reduced by the La/Ba doping. All these observations can be understood based on the interplay of the electron doping, change in bandwidth and the anti-site defect concentration. [Copyright &y& Elsevier]