Electrical, magnetoresistance and magnetotransport properties of Nd1−xSrxMnO3

The effects of Sr substitution on the electrical, magnetoresistance and magnetotransport properties of Nd1−xSrxMnO3 were studied. Nd1−xSrxMnO3 samples were prepared using the solid-state reaction method with x=0.12, 0.152, 0.22, 0.252 and 0.32. All samples showed an orthorhombic structure, and no impurities were detected when the samples were examined using the X-ray diffraction method. The grain size was between 10 μm and 16 μm for all samples. The sample with x=0.32 showed the smallest grain size and the lowest To value, where To reflects the MnOMn bond angle. As the Sr concentration increased, the grains grew into more pentagonal and hexagonal shapes, and the insulator–metal transition temperature, Tim, also increased from 131 K to 180 K. The exceptions were the samples with x=0.152 and 0.252, where charge ordering was found at 120 K. The samples with the most pentagonal and hexagonal shaped grains (x=0.32) had the highest Tim. The magnetoresistance (MR) values were found to increase with increasing magnetic field. The sample with x=0.32 showed the highest MR value (31.5%), the highest Tim, the smallest grain size (∼10 μm) and the least bending of the MnOMn bonding angle.