Magnetic properties and tunneling magnetoresistance in FeCo-SiO2 granular films

Fe-fv(SiO2)(1-fv) granular films were fabricated by rf sputtering (f(v) rep resents the Fe volume fraction). The microstructure, magnetic properties as well as the tunneling magnetoresistance effect (TMR) were systematically s tudied. It was found that the maximum TMR ratio is about -3.3% at f(v) = 0. 33. Under the same condition, a series of (Fe100-x Co-x)(0.33)(SiO2)(0.67) were prepared. TMR value reaches -4.5% at x = 53, while the microstructure of the film still keeps as that of Fe-0.33(SiO2)(0.67). The higher TMR rati o is contributed to the elevating of the spin polarization of particles. Th is is consistent with Inoue's theory.