High frequency properties of Ni75Fe25-SiO2 granular thin films with very high resistivity

Excellent soft magnetic properties have been achieved in low metal volume fraction(x ∼ 0.52) of (Ni75Fe25)x(SiO2)1−x granular film fabricated by magnetron sputtering. The coercivity of 247 A m− 1 with very high resistivity ρ over 1.18 × 104 μΩ cm has been obtained. At the frequency lower than 1 GHz, the real part μ′ of the complex permeability keeps about 55 and the imaginary part μʺ is less than 2. A combined study of TEM and XRD indicates that the sample consists of Ni75Fe25 particles uniformly embedded in insulating SiO2 matrix. The excellent soft magnetic properties are ascribed to the magnetic dipole interaction between particles. The investigations of field cooled and zero field cooled curves as well as Henkle Plot prove the existence of this intergranular interaction.