Synthesis and enhanced low-field magnetoresistance in La0.67Ca0.33MnO3 /CuO composites

The (1−x)La0.67Ca0.33MnO3+xCuO composites have been synthesized by a new liquid phase method. The XRD and SEM measurements reveal that little CuO is soluble in the structure of La0.67Ca0.33MnO3 and is mainly distributed at the grain boundary of La0.67Ca0.33MnO3. As CuO content xx increases, the magnetization MM values increase until x=0.05x=0.05 and MM values decrease when xx further increases at low temperature. For x=0.10x=0.10, 0.20 and 0.30 composites, double metal–insulator transitions accompanying a single ferromagnetic transition are observed. Large low-field magnetoresistance is achieved for the composites and the largest magnetoresistance appeared when x=0.20x=0.20.