Textured CoRu‐substituted BaM hexagonal ferrite with high magnetic resonance frequency and low loss

Abstract The demands of ferrites with high permeability and low‐loss properties are significantly increased within the sub‐6 GHz band. However, traditional spinel and planar hexagonal ferrites, constrained by Snoek’s limit, struggle to meet the requirement of high operating frequency. This study introduces a novel approach by preparing textured CoRu‐substituted BaM hexaferrite incorporating Bi 2 O 3 additives, using high aspect‐ratio goethite precursors. Compared to ferrite synthesized through the conventional solid‐state reaction method, the optimized ferrite demonstrates remarkable improvements in maximum operating frequency (from 0.82 to 7.5 GHz) and performance factor PF (increasing from 23.7 to 98.2 GHz), while maintaining a low magnetic loss (~ 0.10). Magnetic spectrum analysis indicates that the goethite‐derived textured microstructure effectively increases the natural resonance frequency by enhancing the uniaxial magnetic anisotropy, facilitating the achievement of high operating frequency. Differential phase contrast (DPC) results show that adding Bi 2 O 3 broadens the magnetic domain and shifts the domain wall resonance peak to a lower frequency, distinguishing it from the natural resonance peak. Furthermore, compared with the pure dielectric material, the antenna designed using this ferrite exhibits a 17% reduction in size. This study presents a strategy for fabricating textured CoRu‐substituted BaM hexaferrites without the necessity for an external magnetic field and elucidating the regulation mechanism of microstructure on high‐frequency magnetic properties, and offering a novel magneto‐dielectric material that enhances uniaxial magnetic anisotropy while modifying the magnetic domain structure for the sub‐6 GHz band.