Multiple Excitations of Spin Wave Modes in Thin Films

Abstract

Spin wave resonances in thin films are studied as a function of the angle between the field and the film plane in external fields above as well as below the demagnetizing field 4πM. Resonance fields or frequencies for spin wave modes are calculated by a theory in which the static equilibrium conditions and the resonance equation are taken into consideration on the basis of the surface-spin-pinning model and single-domain analysis. The theory predicts that two or three excitations of the identical mode occur when the frequency, the spin wave vector, and direction of field satisfy certain conditions. This multiple-excitation of the mode is confirmed experimentally in Permalloy thin films by employing the field modulation method at a frequency of 100 kHz.