Lorentz TEM studies of Fe-based magnetic materials

초록

Fe-based magnetic materials are widely used for inductor and magnetic recording applications because they have good magnetic properties such as high saturation magnetization, low core loss, low coercivity and high initial permeability. Recently, the soft magnetic materials require large saturation magnetic flux density (Bs) and low coercivity due to increasing requirement of miniaturization for the electromagnetic devices. The power loss is attributed to magnetic microstructures as well as domain wall motions and the origin of the loss has not yet been fully understood. In this work, we analysed the Fe-based magnetic materials, i.e., Sendust(Fe-Si-Al), Permalloy(Ni-Fe) and Fe-based nanocrystalline alloys by Lorentz TEM. Magnetic domain walls and microstructures were observed in a Fe-Si-Al flake particle. Furthermore, the domain wall motions in an electroplated Ni80-Fe20 thin film was observed in-situ. The magnetic hysteresis curves and magnetic permeability were measured by MPMS(Magnetic properties measurement system) and Impedance analyzer, respectively. The correlation between magnetic microstructure and magnetic domain walls will be discussed.