Magnetoresistance in magnetite films prepared from aqueous solution at room temperature

Polycrystalline iron oxide films, 0.1-1.1 mu m in thickness, are synthesize d on glass substrates at room temperature directly from an aqueous solution of FeCl2 by ferrite plating. The films have a single phase spinel structur e of mixed solution (Fe3O4)(1-x)-(gamma-Fe2O3)(x), as revealed by x-ray dif fractometer and conversion electron Fe-57 Mossbauer spectroscopy. At room t emperature the films exhibit negative magnetoresistance (MR) of ratio Delta R/R=-3.3% to -7.4%, which is ascribed to intergranular tunneling of spin p olarized electrons of Fe3O4. The resistivity R of the films is 2.2x10(0)-1. 3x10(3) Omega cm, much higher than that (similar to 10(-2) Omega cm) report ed for bulk samples of Fe3O4; R and Delta R/R depend on the plating conditi ons and, therefore, the composition x in (Fe3O4)(1-x)-(gamma-Fe2O3)(x) of t he samples. (C) 2000 American Institute of Physics. [S0021- 8979(00)67108-6 ].