Magnetoresistance properties of 0.99La0.7(CaxSr1−x)0.3MnO3/0.01CuZnFe4O4 composites

The composites of 0.99La0.7(CaxSr1−x)0.3MnO3/0.01CuZnFe4O4 (LCSMO/CZF) (x = 0, 0.1, 0.2, 0.3, 0.5, 0.7 and 1) were fabricated by conventional solid state reaction method, and their electrical transport and magnetoresistance (MR) properties were investigated by physical property measurement system (PPMS). The result of X-ray diffraction (XRD) and scanning electronic microscopy (SEM) indicated that no new phase appeared in the composites except LCSMO and CZF phases. CZF is mainly distributed at the grain boundaries and surfaces of the matrix. The resistivity of all the composites was measured in the range 100-350 K at 0 T, 0.5 T and 1 T magnetic field. Room temperature MR peak appears for the composites x = 0.03. The observed variation of MR with varying Ca and Sr concentration has been qualitatively.