The precursor phases of SrFeO3–x (SFO) and SrMoO4 (SMO) were used to prepare Sr2FeMoO6 with different ratios by a solid-state reaction technique. An X-ray diffractometer was used to identify the phases. SMO was observed to exist in the Mo-rich samples. The high resolution of a transmission electron microscope was employed to identify the compositions and phases. It was further evidenced that Mo-rich nanosized clusters were located inside the grains rather than at grain boundaries. Moreover, the antiphase boundary was clearly evidenced in the Mo-rich SFMO, which might lead to the Sr- or Fe-rich boundaries. The conduction, magnetic, and magnetotransport properties were characterized, and it was found that the Mo-rich samples had higher resistivity, lower saturated magnetization, and lower coercivity but higher low-field magnetoresistance (LFMR), which was strongly related to the presence of the excess Mo ions and APBs inside the grains. The conduction of SFMO samples with different ratios revealed a semiconductor behavior, which could be described by the VRH model, Eq. (1), with p = ¼ and ρo independent of temperature at 50 to 300K. The evaluated values of To increased with the decrease of the SFO/SMO ratio, which were considered to be influenced by the residual SMO and APBs inside the grains. It was suggested that the enhancement of LFMR of Mo-rich SFMO arose from the APBs or the induced Sr- or Fe-rich grain boundaries.

Reassessment of the Role of Antiphase Boundaries in the Low-Field Magnetoresistance of Sr2FeMoO6. T.T.Fang: Physical Review B, 2005, 71[6], 064401 (7pp)