Size dependence of the magnetization vector reversal processes in epitaxial Fe(001) microstripes

We report the size dependence of the magnetization vector reversal process in micron range rectangular magnetic microstripes fabricated from an epitaxial Fe/GaAs(001) film of thickness 150 Angstrom. The microstripes were of length 100 mu m, widths (w) in the range 5 less than or equal to w less than or equal to 50 mu m and aligned with the long axis parallel to either the [010] or the [110] Fe crystallographic axes. Measurements of the hysteresis loops were performed on these microstripes. For field orientation parallel to the long axis a transition from two-jump to single-jump switching is found to occur for w less than or equal to 20 mu m. An analogous transition from single-jump to two-jump switching occurs for the field applied parallel to the short axis. We show that these results can be explained in terms of the competition between the dipolar and intrinsic uniaxial anisotropy fields. We conclude that the switching is principally determined by local dipolar fields and not by the average demagnetizing fields within the microstripes.