Magnetic properties and dielectric properties of CoFeB/NdFeB composite films at Terahertz

The surface morphology, magnetic properties, exchange coupling and dielectric properties of CoFeB/NdFeB composite films were systematically investigated. The saturation magnetization (Ms) decreases with the increase of CoFeB layer thickness and the magnetic anisotropy field (Hk) reaches minimum when the thickness of CoFeB layer is 200 nm, which indicates the composite films can be applied to electromagnetic shielding with precise control of magnetic field distribution. The real part of the dielectric constant increases first and then decreases with the increase of the thickness of CoFeB film at 75-110 GHz frequency range. The magnetic permeability of the composite films reaches maximum value when the thickness of the CoFeB layer is 200 nm, and the application frequency can be adjusted by CoFeB film thickness, which indicates that the composite films have good electromagnetic response characteristics. It is an ideal choice for high-performance microwave devices in telecommunications equipment.