Structural and magneto-transport properties of (La0.6Ca0.2Sr0.2MnO3)1−x (Sb2O3/CuO)x composites

The (La0.6Ca0.2Sr0.2MnO3)1−x(Sb2O3/CuO)x (x=0.00, 0.03, 0.07, 0.12 and 0.18) composites were prepared by the solid-state reaction technique. (La0.6Ca0.2Sr0.2MnO3)1−x(Sb2O3/CuO)x are identified by X-ray diffraction and SEM analysis as a two phases consisting of ferromagnetic manganite phase and Sb2O3/CuO phase. Magnetic measurement reveals that the Curie temperature as well as the saturation value of magnetization is gradually weakened by Sb2O3/CuO addition. The temperature dependence of resistivity shows that the transport behavior of the composites is governed by the grain boundaries. It is suggested that the Sb2O3 addition, acts as a separation layer between grains. Whereas, the introduction of CuO into the grain boundaries forms artificial conducting network and improves the carrier to transport. The maximum magnetoresistance was observed to be ≈60% at 10 K for x=0.03 which is larger than the largest MR value of pure La0.6Ca0.2Sr0.2MnO3 (40% at 10 K) in a 2 T magnetic field. Enhanced MR effect at a wide temperature range is consistent with the disorder-driven amplification of spin-dependent transport.