Enhanced magnetic anisotropy in structure, static, and dynamic magnetic properties for Ba_3−xLa_xCo₂Fe₂₄O₄₁ hexaferrites

Co₂Z is a planar ferrite, particularly suitable for soft magnetic applications. There is currently a lack of in-depth research on its high-frequency properties. La³⁺ ion is a potential ion to regulate its magnetism. Based on this, the crystal structure, microstructure, static, and dynamic magnetic properties of Ba_3−xLa_xCo₂Fe₂₄O₄₁ (x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.25) ceramics were investigated. The findings demonstrate that La substitution retains the crystal structure and form, yet the introduction of extra charge leads to the formation of Fe²⁺ ions, resulting in a slight decrease in magnetic moment from 51.9 to 48.9 emu/g, while a notable increase in the out-of-plane anisotropic field from 12.2 to 18.3 kOe, which significantly impacts the high-frequency complex magnetic permeability spectrum. Additionally, a thorough analysis of the high-frequency magnetic spectrum indicates that both domain wall movement and magnetization rotation contribute to the magnetic permeability, with magnetization rotation playing predominant. Particularly exciting is that the high-frequency magnetic spectrum results show that the substitution of La for Ba considerably raises the resonance frequency from 2.41 to 3.30 GHz that can be attributed to the increased anisotropy. In conclusion, the substitution of La markedly enhances the high-frequency magnetic properties of Co₂Z.