High-frequency magnetic properties of FeB nanochains based soft magnetic composites for potential antenna applications up to GHz

Soft magnetic materials are a kind of promising materials for antenna substrates because their permeability and permittivity are both greater than unity. However, their magnetic properties would deteriorate dramatically as the frequency reaches 1 GHz owing to Snoek limit and domain wall resonance, thus limiting their application at high frequency. Here, we report a low-dimensional soft magnetic composite (SMC) prepared by FeB nanochains, achieving the optimized magnetic loss tangent (tanδμ) of 0.09 and the real part of permeability (μ′) of 3.3 at 1 GHz, which is more competitive than the conventional spherical FeB SMCs. Such an optimization is ascribed to the change in the dominant mechanism of the magnetization process from domain wall motion to magnetic moment precession, associated with the transition of the magnetic domain structure of the particles from multi- to mono-domain. The SMC proposed in this work provides a significantly potential candidate for high-frequency and miniaturized 5G antennas. Furthermore, the design concept and preparation method can be extended to other SMCs, providing a guidance for the development of high-performance antenna substrate materials.