Ultra-low core loss in Fe-enriched soft magnetic ribbons enabled by nanostructure and high-frequency domain engineering.

The next generation of power electronics necessitates materials capable of rapid response at tens of kilohertz frequencies while ensuring minimal core losses. Accelerating the advancement of power electronics hinges on addressing the current shortage of ultra-low core loss soft magnets, thereby enabling sustainable energy utilization and paving the way toward achieving zero carbon footprints. Here we demonstrate an approach that integrates nanostructure engineering with high-frequency domain structure control, significantly enhancing the performance of Fe-enriched amorphous ribbons. Our strategy reduces core loss by 55%, achieving an ultra-low loss of ~ 75 ± 1.3 W/kg at 10 kHz, 1 T. We attribute this improvement to optimized perpendicular magnetic anisotropy, which is induced by positive magnetostriction and compressive stress generated from partial nanocrystallization of α-Fe in a residual amorphous matrix. These configurations lead to the formation of a narrow stripe-shaped magnetic domain (~ 4.8 ± 0.6 μm wide), resulting in minimal excess loss. These findings highlight a pivotal advancement in soft magnet design, facilitating energy-efficient, miniaturized power electronics for modern applications.