Fabrication and study of Ni/sub 75/Fe/sub 25/-SiO/sub 2/ granular films for high frequency application

Ni/sub 75/Fe/sub 25/-SiO/sub 2/ granular films are fabricated and studied for high frequency applications. The films of different metal volume fraction f/sub v/ are fabricated by magnetron co-sputtering and they have fcc Ni/sub 3/Fe structure determined by X-ray diffraction. Magnetic hysteresis loops show that the samples of f/sub v/=0.81 have in plane uniaxial anisotropy. The resistivity /spl rho/ is shown to increase slowly with decreasing f/sub v/ then increases rapidly after f/sub v/>0.7, while coercivity H/sub c/ decreases rapidly as f/sub v/ decreases from 0.81 to 0.52 and does not exceed 5 Oe. In this f/sub v/ range, good soft magnetic properties are obtained especially for the sample with f/sub v/=0.52 in which /spl rho/ reaches 19000 /spl mu//spl Omega//spl middot/cm with negative temperature coefficient. This high /spl rho/ effectively depresses the eddy current loss as applying for high frequency range. These interesting behavior is understood by exchange coupling between nanoparticles.