MICROSTRUCTURE AND MAGNETISM OF (Fe_65Co_35)_x(SiO_2)_(1-x) NANO-GRANULAR FILM

(Fe65Co35)0.42(SiO2)0.58 granular film consisting of FeCo nanoscale magnetic granules embedded in SiO2 matrix was fabricated by radio frequency (RF) magnetron sputtering. Excellent soft magnetic properties with anisotropy field Hk = 3 820 Am-1, coercivity in easy axes low as to as 143 Am-1 and resistivity up to 13.4 mΩ·cm were obtained after the sample was annealed in a magnetic field at low temperature. At a frequency lower than 0.7 GHz, the real part μ′ of complex permeability of this sample is above 100 and the FMR frequency is as high as 1.8 GHz, implying a high cut-off frequency for high frequency applications, which makes it promising in the applications in high frequency device and anti-jamming technology. It was proved by ferromagnetic resonance that the good soft magnetic properties in this sample come from the ferromagnetic intergranular exchange coupling.