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 （Po2） from 0 to 11.7%, and the electrical and magnetic properties of films have been studied. It is shown that optimal Fe43.29 Co19.51Hf7.49 O29.71 films with desired properties can be obtained when the films were prepared under Po2= 5.1%. The films show superior properties of low coereivity, Hc ∽5.5 Oe, relatively high saturation magnetization, 47rMs · 18.3 kG, high anisotropy field Hk ∽ 65 Oe, and high electrical resistivity ρ∽ 2675 μΩ·cm. 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.     

Theoretical Investigations on the Off-Center Displacement of Co2+ in SrO by Analyzing Its Anisotropic g Factors

The off-center displacement of Co^2＋ ion in SrO crystal is investigated by analyzing its anisotropic g factors gx, gy and gz through diagonalization of the 6 × 6 energy matrix within ^4T1 ground state for a 3d^7 ion under rhombic symmetry. In the matrix, the contributions from the admixtures of various J（= 1/2, 3/2, 5/2） states and the fourth-order term Dn of rhombic crystal-fields and the ligand orbitals and spin-orbit coupling interactions, which are usually ignored in the previous studies, are considered. Both g factors （gx = 4.172, gy = 5.004 and gz = 2.133） and the off-displacement value （△ R ≈ 0.023 am） show good agreement with the experimental data.