A combined microwave-magnetic-resonance and Brillouin-scattering experiment is used to probe the spatial variation of the rf magnetization in a film of yttrium iron garnet under resonance. In a nonuniform field the measured variations agree well with the eigenfunctions of a Schrödinger-like equation derived from the magnetostatic equations. The results provide a simple explanation for the mechanism of dipolar narrowing of ferromagnetic resonance lines in a nonuniform field.

• Received 18 March 1991

DOI:https://doi.org/10.1103/PhysRevB.44.7062