Synthesis and enhanced low-field magnetoresistance in La 0.67Ca 0.33MnO 3 /CuO composites

Abstract

The (1− x)La 0.67Ca 0.33MnO 3+ 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 La 0.67Ca 0.33MnO 3 and is mainly distributed at the grain boundary of La 0.67Ca 0.33MnO 3. As CuO content x increases, the magnetization M values increase until x = 0.05 and M values decrease when x further increases at low temperature. For x = 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 = 0.20 .