Fast Switching by Domain Walls in Ferrites

Experimental evidence indicates that small grain size is associated with faster domain wall switching in ferrite cores. It has been shown by H. Amar that small grain size contributed an additional energy to the wall energy density ${\sigma }_{\omega }$ . Incorporation of this energy into the power equation ${\mathrm{H\hspace{0.17em}·\hspace{0.17em}(dM/dt)\hspace{0.17em}=\hspace{0.17em}\lambda H}}_e^2$ reveals that the loss coefficient decreases more than ${\sigma }_{\omega }$ increases, and, therefore, faster switching results. A qualitative explanation is given for faster switching by domain walls in magnetic materials. The significant variables in the switching coefficient equation are “$d$ ,” $T_c$ , $K$ , and $\alpha$ . Experimental data show that the switching coefficient is lowered by decreasing values of the first three variables. Considerably faster switching is predicted when similar cores with grain sizes less than 1 μ are made.