Enhanced magnetoresistance of La2/3Ca1/3MnO3/CeO2 nanocystalline composites synthesized by polymer-network gel method

Using a dispersing particle polymer-network gel method, we prepared xLa2∕3Ca1∕3MnO3∕(1−x)CeO2 nanocystalline composites, where the average grain sizes of La2∕3Ca1∕3MnO3 and CeO2 are about 30nm and less than 10nm, respectively. The magnetoresistance of the sintered composites is explored as a function of the ratio of metal/insulator, temperature, and magnetic field. The system exhibits metallic percolation threshold at x=xp∼35%, around which the high field magnetoresistance has a maximum (∼70%) at 50K and 5T, and the low field magnetoresistance value is close to 16% at 5K and 0.05T.