How to choose new materials to improve the magnetic permeability of millimeter wave materials

AbsorberWidely used in various fields such as consumer electronics, security, communication, automotive, medical, aerospace, etc. Especially with the continuous improvement of requirements for millimeter wave radar, LiDAR, cameras, etc. in intelligent driving, the demand for millimeter wave absorbing materials is also increasing.Millimeter wave absorbing materialsThe application of intelligent driving can not only effectively prevent electromagnetic interference (EMI), but also ensure electromagnetic information security, reduce electromagnetic radiation, and improve the safety and comfort of intelligent driving.
Magnetic permeability is one of the important magnetic performance parameters for measuring absorbing materials. According to the principle of absorption and reflection of electromagnetic waves, when electromagnetic waves reach the surface of a material, only a small part of the electromagnetic waves will be reflected, while the majority of the electromagnetic waves will enter the interior of the absorbing material, converting electromagnetic energy into thermal energy in the form of magnetic loss, eddy current loss, dielectric loss, and other losses, achieving the purpose of absorbing waves.

As the application frequency increases, this loss will gradually increase. Most materials experience rapid losses and very low magnetic permeability in the millimeter wave application frequency band. Therefore, improving the magnetic permeability of millimeter wave materials to reduce or delay losses is always a worthwhile research topic.
There are two main ways to improve the magnetic permeability of millimeter wave materials:
1. Change the intrinsic parameters of the material
1. Reduce internal stress ξ
2. Increase the saturation magnetization Ms
3. Reduce the magnetic crystal anisotropy constant K1
The saturation magnetization, magnetic crystal anisotropy constant, and internal stress are three important intrinsic characteristics that affect the magnetic permeability of materials. They can be adjusted by selecting appropriate materials and using mechanical and chemical treatment methods. 2. Breaking through Snoek's limits
1 nanometer crystallization
2 Flattening
3 Fibrosis
The appearance and size of the product are two important factors in breaking through Snoek's limits. The size and morphology of materials can be altered through techniques such as nanocrystallization, flattening, and fibrosis to achieve higher magnetic permeability.
Improving magnetic permeability is just one of the ways in which millimeter wave materials can be better applied in the high frequency range. Other application methods, such as using different thicknesses and stripe combinations on FeCoBSi thin films, can expand microwave resonance and frequency band to meet EMI requirements [2]; Utilizing an ultra-thin material with a stepped structure to enhance its application in the high-frequency range [3] and so on;