Fig. 3. Soft magnetic response and associated Bloch wall motion behaviour of the MCAs at room temperature.
a, Hysteresis loops (M/H) acquired up to ±800 kA m−1. The magnetic-field-sweeping rate is 1 kA m−1. The inset shows the enlarged view of the increase in saturation magnetization with particle coarsening. b, M/H curves measured at a rate of 0.1 kA m−1 between ±50 kA m−1, showing the extremely low coercivity. c, MOKE microscopy observation, in longitudinal contrast, showing the magnetization process. The applied magnetic field is horizontal to the viewing plane. d, Statistical particle size distribution of all the MCAs under different isothermal heat treatment conditions (1–100 h at 1,173 K). The inset shows the evolution of particle size by ECCI probing.