Torque distribution along the axis at (a) t = 0, (c) t = 5 t₀, (e) t = 6 t₀, and (g) t = 10 t₀ in SES, and (b) t = 0, (d) t = 5 t₀, (f) t = 14 t₀, and (h) t = 20 t₀ in FES, where the positive (negative) torque promotes the counterclockwise (clockwise) rotation is shown in red (purple). In all panels, the magnetic contours of +20 Gauss (dark red) and -20 Gauss (dark blue) are superimposed on the bottom plane. The white lines show polarity inversion lines in each panel. An animation showing the above evolutions is available online.