Potassium doping effects on the structure and magnetic properties of Sr2FeMoO6

► Potassium is successfully incorporated in Sr2FeMoO6. ► The AS defect in Sr2FeMoO6 may be adjusted by potassium doping. ► The magnetoresistance of the series is sensitive to vacancies content. ► Fe may increase the valance state after potassium doping and Mo remain that unchanged. ► The unit cell magnetization at 280 K is 1.12 μB for x = 0 and 1.26 μB for x = 0.04, respectively.