Fabrication and Study of Ni Fe -SiO Granular Films for High Frequency Application

A series of (Ni Fe ) (SiO ) films with different volume fraction is fabricated by magnetron co-sputtering technique. The structure, magnetic and high frequency properties are investigated systematically by X-ray diffraction, transmission electronic microscopy, vibrating sample magnetometer, resistivity and complex permeability measurements. The results show that the films consist of Ni Fe magnetic metal particles uniformly embedded in the insulating SiO matrix. The (Ni Fe ) (SiO ) films exhibit excellent soft magnetic properties in a wide range from 0.81 to 0.52 with coercivity not exceeding 5 Oe, which is ascribed to the exchange coupling between magnetic particles due to the long exchange length of Ni Fe alloy. The smallest is 1.1 Oe obtained for the sample of 0.81 with high electrical resistivity 167 cm, and the real part of its initial complex permeability keeps constant of 170 below 550 MHz while the imaginary part is less than 26. The rapid increase of at the frequency higher than 600 MHz can be attributed to the ferromagnetic resonance, whose frequency is estimated to be about 2.2 GHz. For the film of 0.52, besides the low ( 3 Oe), very high over 1.18 10 cm has been obtained, implying that this film is quite promising for very high frequency application.