Magnetic characterization of grain boundaries in electrical steel using the magneto-optical Faraday effect incremental permeability and principal component analysis

Background: Grain boundaries in electrical steel influence magnetic properties and energy losses, but their localized magnetic behavior is challenging to characterize. Objective: To develop a high-resolution, non-destructive method to characterize grain boundaries using the Magneto-Optical Faraday effect, Magnetic Incremental Permeability (MO-MIP), and Principal Component Analysis (PCA). Methods: We used MO-MIP and applied PCA to the resulting data to extract localized magnetic variations at grain boundaries in grain-oriented electrical steel samples. Results: The proposed method successfully detected differences in magnetic behavior at grain boundaries. However, spatial resolution was limited by the mismatch between the laser spot size and the narrow grain boundary width. Conclusions: The MO-MIP method with PCA demonstrates strong potential for high-resolution, non-destructive evaluation of grain boundary magnetic properties, though further improvements in spatial resolution are needed.