La and Co doping effects on magnetoresistance of double perovskite Sr2FeMoO6

Double perovskite Sr2FeMoO6 (SFMO) with composition of Sr2-xLaxFe1-yCoyMoO6 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 at.%; y = 0, 0.05, 0.1, 0.2, 0.3, 0.5, 0.9 at.%) was synthesized by high energy ball milling and sintering. The sintered samples were investigated by means of X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and magnetic measurements. XRD results show that all the samples have single phase double perovskite structure. EDS spectrum confirmed that the actual composition of prepared samples is in agreement with nominal ones. With the increase of doping concentration of La, the magnetization decreases, whereas Curie temperature increases in SFMO. And with doping concentration of La, the magnetoresistance (MR) ratio with a low magnetic field of 480 kA/m increases, has its maximum value as 5% for x = 0.3 at 293 K. The degree of antisite disorder decreases with Co2+ doping, and therefore results in increase of MR ratio. At room temperature, the MR ratio with a considerable low magnetic field for x = 0.3, y = 0.1 has maximum value as 6.5%.