High-frequency properties of [Co90Nb10/Ni0.45Zn0.55Fe2O4(t)]6 multilayer films for application in GHz range

A series of [Co90Nb10/Ni0.45Zn0.55Fe2O4(t)]6 multilayer films were fabricated on Si(111) substrates by means of radio frequency magnetron sputtering. The influences of Ni-Zn ferrite interlayer thicknesses (t) on the static and high-frequency soft magnetic properties of multilayer films have been investigated. As increasing the ferrite thickness (t) from 0 to 6 nm, the saturation magnetization Ms decreased from 876 emu/cm3 to 488 emu/cm3, but the in-plane uniaxial magnetic anisotropy effective field Hk and electrical resistivity ρ varied from 17 Oe to 52 Oe and from 170 µΩ cm to 3670 µΩ cm respectively. As a consequence, the resonance frequency fr of the multilayer films were continuously increased from 1.45 GHz to 2.7 GHz. The results showed that the interlayer ferrite thickness had an important effect on magnetic properties of the multilayer films and that it can be convenient to adjust the natural resonance frequency.