Anti-site Defect Versus Grain Boundary Competitions in Magnetoresistance Behavior of Sr2FeMoO6 Double Perovskite.

The competitive effects of Fe/Mo anti-site defect (ASD) concentration and grain boundary (GB) property on the magnetoresistance (MR) behavior of Sr₂FeMoO₆ (SFMO) double perovskite are investigated. Two SFMO samples with different ASD concentrations (31% and 14%) were prepared by controlling the different sintering temperature, and then, they were performed several GB modifying treatments. While the ASD remain unchanged, the MR values of both samples were appreciably enhanced since more than thousand times of resistivity had been increased after GB modifying. When compared samples that under the same soaking treatments, the more disorder sample (ASD = 31%) always showed the lower MR value than the ordered (ASD = 14%), regardless of its stronger GB strength. This suggests that the negative effect of ASD always plays an important role in MR behavior and this adverse effect is hardly offset by the increased positive effects of its GB property. [ABSTRACT FROM AUTHOR]