Reprogramming magnetic anisotropy: Field-assisted annealing of Fe-based bulk metallic glass ribbons

Fe-based bulk metallic glasses (BMGs) are recognized for their excellent soft magnetic properties, further tunable through thermal processing. In this study, we investigate the effects of zero-field and field-assisted annealing on crystallization and stress-driven magnetic properties of Fe 8 0 B 12 P 4 Si 2.7 C 1.3 melt-spun ribbons. Using Kerr microscopy and magnetic measurements, we analyze the evolution of magnetic domains, anisotropy, and stress relaxation under different annealing conditions. Our results reveal that magnetic-field-assisted annealing below the Curie temperature effectively suppresses crystallization while reprogramming magnetic anisotropy, leading to improved soft magnetic properties. Reprogramming the magnetic anisotropy by annealing in a longitudinal magnetic field of 16 kA/m is effective only when the system remains fully amorphous. In a partially crystallized system, local anisotropy dominates over field-induced anisotropy. These findings clarify the thermal and structural conditions required for controlled tuning of magnetic anisotropy and soft magnetic performance, providing deeper insight into the interplay between stress, crystallization, and magnetic anisotropy in Fe-based BMGs. • Stress in Fe-B-P-Si-C melt-spun bulk metallic glass ribbons is visualized by imaging magnetic domains. • Field-assisted annealing below the Curie temperature suppresses crystallization and reprograms magnetic anisotropy. • Crystallization-induced anisotropy competes with field-induced anisotropy in partially crystallized BMGs. • Zero-field and field-assisted annealing have the same effect on the structural and magnetic properties of the metallic glasses above the Curie temperature.