Structural Modulation of Magnetic Softness in Fe‐Based Amorphous Alloys via Pulse Current Training

ABSTRACT Fe‐based amorphous alloys, despite their intrinsically low magnetocrystalline anisotropy, suffer from quasi‐dislocation dipoles and localized stress fields that impede domain‐wall motion and increase coercivity. Here, we introduce pulse current training (PCT) as an energy‐efficient technique to overcome these limitations in a Fe 76 Si 9 B 10 P 5 ribbon. As quenched ribbons exhibit a coercivity H c ∼ 10.6 A m −1 and the optimized infrared annealing reduced H c ∼ 2 A m −1 with a saturation magnetization M s ∼ 162 emu g −1 . By applying controlled square‐wave current pulses ( J = 7000 A cm −2 , T w : T p = 1:2, T p = 0.06 s) over 18–50 cycles, PCT further reduces H c to below 1 A m −1 and increases M s to 179 emu g −1 . Within a moderate‐cycle window, the ribbons maintain sufficient bendability for a practical core. Ultra‐rapid thermal annealing performed as a control reduces H c to ∼2.5 A m −1 but does not reach the level achieved by PCT, indicating that rapid heating alone cannot account for the superior magnetic softening. Finite‐element simulations and structural characterization show that PCT produces rapid and nearly uniform Joule heating, enabling efficient structural relaxation and enhanced medium‐range order while retaining an overall amorphous structure. Compared with conventional annealing, PCT implements a distinct, pulse energy injection pathway on the potential energy landscape, enabling more controllable tuning of amorphous configurations. This work establishes PCT as a versatile approach for tailoring both magnetic and mechanical properties in amorphous soft magnetic materials, paving the way for their optimized application in advanced electromagnetic devices.