Electrical transport properties and enhanced broad-temperature-range low field magnetoresistance in LCMO ceramics by Sm2O3 adding

Abstract

Polycrystalline La0.67Ca0.33MnO3 (LCMO) ceramics were prepared by the sol-gel method. LCMO/mol%(Sm2O3)x (LCMO/(SO)x, x = 0, 0.01, 0.03, 0.05, 0.10) ceramics composites were synthesized using solid state sintering. Effects of Sm2O3-adding on the structures, electrical transport and magnetoresistance properties of the as-prepared LCMO/(SO)x samples were studied. The refinement of the X-ray diffraction (XRD) patterns showed that the lattice parameters (a, b, c, V) of LCMO are slightly decreased, indicating Sm3+ ion substitution of A-site rose. Field emission scanning electron microscope (FE-SEM) study confirmed the composite structure of LCMO/(SO)x ceramics samples. At x ≤ 0.03, the temperature dependence of resistivity shows a double insulator-metal (I-M) transition. While at x ≥ 0.05, it exhibits a single I-M transition with broad transition width at low temperature. An interesting and important result for the present LCMO/(SO)x ceramics composites is the observation of the enhanced transversal low-field magnetoresistance (LFMR) at low applied magnetic field of 300 and 500 mT over a broad temperature range of below ∼ 260 K.