Light scattering study on surface magnons in permalloy films

摘要

Brillouin light scattering has been used to study the critical angle behavior for magnetostatic surface waves (MSSW) in thin permalloy films on silicon substrates. The measured magnon frequency versus wave number for various MSSW propagation angles with respect to the applied in‐plane static field show that (i) for propagation perpendicular to the applied field, there is good agreement between the experimental and theoretical dispersion; (ii) for propagation away from perpendicular, the experimental frequencies are smaller than the theoretical values; and (iii) the surface mode merges with the zero‐order bulk spin wave mode at a propagation angle well above the theoretical critical angle. These results demonstrate a significant departure from existing theories.