Tunneling magnetoresistance in BaTiO3/Fe3O4 composites

概要

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(1-x)BaTiO3-xFe3O4 composites were successfully prepared by conventional solid-state sintering of raw materials (BaCO3, TiO2, and Fe3O4) in the molar fraction x of Fe3O4 to BaTiO3 at 1323 K for 5 hours under Ar gas flow. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements were performed for these samples and it is confirmed that the composites consist of only two phases of BaTiO3 and Fe3O4. The largest saturation magnetization (Ms) of 73.4 emu/g was observed at x = 0.80, which was consistent with the product of the molar fraction of Fe3O4 and the Ms of pure Fe3O4. The largest MR ratio of 4.9% were observed under magnetic field of |H|>6 kOe for the x = 0.75 sample. The MR ratio is quadruple as large as that of Fe3O4. This result suggests that the formation of insulating BaTiO3 barriers and tunneling conduction of spins between Fe3O4-grains cause the large MR ratio in BaTiO3/Fe3O4 granular system.
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