We report a magneto-optical Kerr effect study of the collective magnetic response of artificial square spin ice, a lithographically defined array of single-domain ferromagnetic islands. We find that the anisotropic interisland interactions lead to a nonmonotonic angular dependence of the array coercive field. Comparisons with micromagnetic simulations indicate that the two perpendicular sublattices exhibit distinct responses to island edge roughness, which clearly influence the magnetization reversal process. Furthermore, such comparisons demonstrate that disorder associated with roughness in the island edges plays a hitherto unrecognized but essential role in the collective behavior of these systems.
Physical Review B
- Pub Date:
- November 2011
- Spin glasses and other random magnets;
- Condensed Matter - Mesoscale and Nanoscale Physics
- Physical Review B, Rapid Communications (in press)