Dispersion in thin magnetic films

Measurements have been performed on the angular dispersion in thin magnetic films of Permalloy; an analysis shows that apparent dispersion should exist, even in perfect films, because of demagnetizing fields and magnetization buckling. The analysis and experiments confirm that, in many film samples, dispersion caused by demagnetizing fields is predominant. A phenomenological dispersion theory based on domain rotation, Nee´l wall formation, and demagnetizing fields is proposed. This theory predicts that the apparent dispersion angle and the apparent amplitude dispersion of Hk increase with an increasing demagnetizing field. The theory is found sufficiently accurate to serve as a useful engineering tool.