The effect of strontium non-stoichiometry on the physical properties of double perovskite Sr2FeMoO6

•Strontium nonstoichiometric samples of Sr2FeMoO6 are prepared by a citrate route.•The nonstoichiometric samples exhibit an increased Fe/Mo disorder in the structure.•We observed important changes in their magnetic and magnetoresistive properties.•Improved magnetoresistive properties for samples prepared with strontium excess.

We present a detailed study on the effect of strontium non-stoichiometry on the properties of double perovskite Sr2FeMoO6 (SFMO). A citrate route has been used to prepare high quality polycrystalline samples with (2−x)Sr:Fe:Mo (x=0, 0.02, 0.04) and (2+x)Sr:Fe:Mo (x=0.02, 0.04, 0.10) cationic ratios. The strontium deficient samples exhibit a significant decrease in their values of saturation magnetization (Ms), Curie temperature (Tc) and magnetoresistance (MR) compared to the stoichiometric SFMO. On the other hand, the samples prepared with an excess of strontium, respectively those with x=0.02 and 0.04, show remarkably superior magneto–transport characteristics, despite of their increased level of Fe/Mo disorder and somewhat diminished magnetic properties compared to the stoichiometric SFMO. We also show that these samples exhibit superior MR values under low magnetic field and persisting up to temperatures as high as 400 K.

Graphical abstractEvolution of the magnetization versus temperature under an applied magnetic field of 1000 Oe (left panel) and magnetoresistance versus applied magnetic field at 300 K (right panel) for strontium off-stoichiometric Sr2FeMoO6 samples.Figure optionsDownload full-size imageDownload as PowerPoint slide