Figure 1
Illustration: Alan Stonebraker

Figure 1: (Top) A domain wall in a wire separates regions where the magnetization (indicated by the white arrows) points in opposite directions. The magnified view from the top of the wire shows the spin structure of a transverse domain wall that occurs when the wire is thin and narrow. (Bottom) When the domain wall is displaced by a current pulse it switches its polarity (i.e., the magnetization inside the wall flips from up to down).