GMI enhancement of FINEMET/Fe₂₀Ni₈₀ composite ribbons via post heat treatment

Two different preparation processes of FINEMET/Fe₂₀Ni₈₀ composite ribbons -AFC (Annealing First, then Coating) and CFA (Coating First, then Annealing) were compared. It was observed that the CFA process offers significant advantages in enhancing the soft magnetic properties of magnetic materials, particularly in improving the Giant Magneto-Impedance (GMI) effect. This advantage stems from the CFA process's enhanced capability to effectively alleviate stress between the substrate and the magnetic layer, thereby increasing the transverse permeability of the composite ribbons and ultimately improving the soft magnetic properties of the material. Fe₂₀Ni₈₀ composite ribbons with magnetic layer thicknesses of 100 nm and 150 nm were taken as examples. The ribbons prepared via the CFA process exhibited higher GMI ratios of 89.4 % and 95.4 %, respectively. Those prepared through the AFC process showed GMI ratios of only 52.0 % and 56.0 %, respectively. This comparison clearly shows that the CFA process can more effectively enhance the magnetic properties of composite materials. Further optimization of the preparation process can not only enhance the soft magnetic properties of magnetic materials, but also improve the accuracy of magnetic interaction studies using GMI effect, which is crucial for improving the properties of magnetic materials.