High frequency magnetic properties and intergranule interaction of nano-granular films with high resistivity and high permeability.

In order to get magnetic films with high permeability and high resistivity for applications in high frequency devices, (Fe65Co35)x(SiO2)1-x nano-granular films with low metal volume fraction were fabricated by radio frequency magnetron sputtering, and excellent soft magnetic properties have been acquired by annealing the sample with x = 0.38 at 260 degrees C in a magnetic field. The real part micro' of complex permeability is larger than 100 when frequency f is lower than 0.7 GHz, and the ferromagnetic resonance frequency f(r) is as high as 1.8 GHz. More interestedly, the resistivity of this sample reaches 13.4 momega x cm, 4 orders higher than that of pure FeCo alloy. Ferromagnetic resonance experiment and deltam-H curve study were employed to elucidate the mechanism of soft magnetic properties. The results reveal that the intergranule exchange coupling plays an important role in realizing good soft magnetic properties for metal-insulator granular films.