Magnetic Properties of Fe-Al-O Films on Polyimide Substrates

Fe-Al-O films with high electrical resistivities were prepared on polyimide substrates by reactive dc magnetron sputtering in Ar + O2 gases and by RF co-sputtering of Fe and Al2O3. The relationship between the magnetic properties and resistivities of the films was investigated. The films prepared by RF co-sputtering exibited soft magnetic properties together with high resistivities of more than 103μΩcm. After annealing at 380°C for 1 hour under a field of 1 kOe, a coercivity of 1.5 Oe, a resistivity of 2600μΩcm, an anisotropy field of 6 Oe and a saturation magnetization of 10 kG were obtained. These results are considered to be same values as the nano-granular structure reported on Fe-Al-O films prepared on glass substrates. On the other hand, the films prepared by reactive dc magnetron sputtering did not exibit such soft magnetic properties, because the nano-granular structure was disturbed by the presence of excess oxygen during film deposition.