Enhanced magnetoresistance at high temperatures in La0.7Sr0.3MnO3/silica nanocomposites

La0.7Sr0.3MnO3(LSMO)/SiO2 nanocomposites were prepared by a sol–gel chemical route using tetraethoxy silane as the source of SiO2. XRD patterns and SEM images show that LSMO perovskite and silica are simultaneously obtained. The grain size of LSMO varies slightly with increasing silica content. A significant enhanced magnetoresistance (MR) at high temperatures and under a very low magnetic field is observed in the composites compared with LSMO. Magnetic measurements indicate that the addition of silica gives rise to a magnetic disorder at interfaces due to the formation of silicate. We argue that the MR enhancement is ascribed to the suppression of silicate-induced enhanced spin-dependent scattering of the conduction electrons by the applied magnetic field.