Magnetic and Magnetotransport Properties of (Pr0.7Sr0.3MnO3)1-x/NiOx Composites

In this paper, we report the structural, magnetic and magnetotransport properties of (Pr0.7Sr0.3MnO3)(1-x)/NiOx (x = 0, 0.05, 0.10, 0.15 and 0.20) composites samples. The composite samples have been synthesized in such a manner so that there is no reaction between Pr0.7Sr0.3MnO3 (PSMO) and NiO. This has been confirmed by XRD and FESEM results. The magnetic measurements show reduction in ferromagnetic ordering in the composite samples with increasing level of NiO. Furthermore, incorporation of NiO phase into Pr0.7Sr0.3MnO3 matrix lowers the metal-insulator transition temperature (T-IM) and increases the resistance of composites. An enhancement in magnetoresistance (MR) is observed at low temperature, below 140 K, for the composites with x = 0.05, 0.10 and 0.15 and at high temperature (298K) for all the composites at applied magnetic field H = 5 kOe. It is suggested that the higher value of MR at temperature below 140 K is low field magnetoresistance (LFMR) caused by spin polarized tunneling, whereas at around room temperature it is caused by magnetic disordering.