Effect of second introduced phase on magnetotransport properties of La2/3Sr1/3MnO3/0.33(CuO, ZnO, Al2O3) composites

The structure, magnetic and magnetotransport properties of La2/3Sr1/3MnO3(LSMO)/0.33(CuO, ZnO, Al2O3) composites were investigated to explore the role of second introduced phase. The microstructural analysis shows two kinds of grain boundaries: LSMO/LSMO and LSMO/second phase/LSMO. Two maximal resistivities appear in LSMO/0.33CuO and LSMO/0.33ZnO composites while the resistivity of LSMO/0.33Al2O3 decreases monotonically with increasing the temperature from 200 K to 400 K. Moreover, the temperature dependence of magnetoresistance(MR) of LSMO/0.33Al2O3 that decreases monotonically with increasing the temperature is different from that of LSMO/0.33CuO and LSMO/0.33ZnO. A developed two-channel model consisting of scattering model and tunneling model was proposed to fit the resistivity—temperature curves of these composites. The role of second introduced phase and the magnetotransport mechanism of these composites were elucidated.