Soft Magnetic Thin Films FeCoHfO for High-Frequency Noise Suppression Applications

A series of FeCoHfO films were fabricated by dc magnetron reactive sputtering at varying partial pressure of oxygen (P _O2) from 0 to 11.7%, and the electrical and magnetic properties of films have been studied. It is shown that optimal Fe_43.29Co_19.51Hf_7.49O_29.71 films with desired properties can be obtained when the films were prepared under P_O2= 5.1%. The films show superior properties of low coercivity, H_c~5.5 Oe, relatively high saturation magnetization, 4πM_s~18.3 kG, high anisotropy field H_k~EM>65 Oe, and high electrical resistivity ρ~2675 µΩcm. Permeability spectra shows that the natural ferromagnetic resonant frequency is as high as ~3.1 GHz. The combined merits of the film make the films taken as an ideal candidate material for high-frequency applications such as noise suppressor. In addition, the effects of the film thickness and annealing treatment on the magnetic properties are also reported.