Influence of Magnetic Field Thermal Annealing on the High- Frequency Performance of the FeCo-Based Granular Thin Films

A series of FeCoHfO granular films were fabricated by reactive DC magnetron reactive sputtering at varying partial pressure of oxygen and annealed by magnetic field thermal annealing. By using magnetic field annealing method suitably, the soft magnetic properties of FeCoHfO granular thin films are improved obviously. The optimal annealing temperature and annealing time are 350 °C and 20 minute, respectively. The films with desired properties of low coercivity, Hc~2Oe, relatively high saturation magnetization, 4pMs~20.5 kG, high anisotropy field Hk~50Oe, and high electrical resistivity r ~ 1875mWcm and natural ferromagnetic resonant frequency about 3 GHz have been obtained.