Magnetic domain formation in perforated permalloy films

The magnetization behavior of permalloy films containing a square array of holes has been studied using magnetometry, magneto-optical imaging, and magnetic force microscopy. Two types of domain boundaries are observed. The hole array induces a strongly pinned, complex domain structure on the microscopic level (i.e., within one unit cell of the hole array). We show that magnetization reversal occurs through the nucleation and motion of a domain wall that separates areas of oppositely polarized microscopic domain patterns. These walls display highly mobile kinks that induce the reversal of the microscopic patterns. The interplay between intrinsic anisotropy and pinning by the hole array induces a pronounced anisotropy in the domain patterns and switching mechanism.