Nanostructure and excellent magnetic properties of Co19.35Fe53.28Hf7.92O19.35 films

This letter reports the novel nanostructure and excellent magnetic properties of Co19.35Fe53.28Hf7.92O19.35 films with varying thicknesses. Among the samples investigated, the film with a thickness of 432 nm exhibits the most excellent magnetic properties: high saturation magnetization, 4πMs∼19.86kG, low coercivity, Hc∼1.5Oe, and high hard-axis anisotropy field of Hk∼84Oe. The magnetic permeability remains almost stable up to 3 GHz and reaches a maximum at the ferromagnetic resonant frequency of 4.024 GHz. The excellent magnetic characteristics of this film in addition to a very high electrical resistivity of 3569 μΩ cm make it ideal for uses in high-frequency applications of micromagnetic devices. It reveals that these superior properties are ascribed to the formed peculiar nanostructure. A magnetic phase separation appears to occur strongly as the film thickness increases over 437 nm, which, in turn, modifies the high-frequency behavior.