Magnetoresistance in magnetite films prepared from aqueous solution at room temperature

Abstract

Polycrystalline iron oxide films, 0.1–1.1 μm in thickness, are synthesized on glass substrates at room temperature directly from an aqueous solution of FeCl2 by ferrite plating. The films have a single phase spinel structure of mixed solution (Fe3O4)1−x–(γ-Fe2O3)x, as revealed by x-ray diffractometer and conversion electron Fe57 Mössbauer spectroscopy. At room temperature the films exhibit negative magnetoresistance (MR) of ratio ΔR/R=−3.3% to −7.4%, which is ascribed to intergranular tunneling of spin polarized electrons of Fe3O4. The resistivity R of the films is 2.2×100–1.3×103 Ω cm, much higher than that (∼10−2 Ω cm) reported for bulk samples of Fe3O4; R and ΔR/R depend on the plating conditions and, therefore, the composition x in (Fe3O4)1−x–(γ-Fe2O3)x of the samples.

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