Low-field magnetoresistance in La0.7Sr0.3MnO3/CuCrO2 composites

Two-phase composites of (1−x)La0.7Sr0.3MnO3/xCuCrO2 (x is mass%) are synthesized by the sol–gel method. The microstructure, and magnetic and transport properties of the composites were investigated. Magnetic measurements reveal that the ferromagnetic order of La0.7Sr0.3MnO3 (LSMO) is weakened by addition of CuCrO2. Magnetization drops from 80.1 emu/g in pure La0.7Sr0.3MnO3(x=0) to 40.8 emu/g for x=0.5. Compared with pure LSMO, enhancement of low-field magnetoresistance (LFMR) is observed in the composites. A significant enhancement in magnetoresistance (MR) under an applied field of 5 KOe is observed from low temperature up to room temperature. The MR value at 300 K for the sample with x=0.3 is about 8 times larger than that of pure LSMO. We suggest that the improved MR should be arising from enhanced spin-polarized tunneling caused by magnetic disorder.