Ferromagnetoelastic Resonance in Thin Films. I. Formal Treatment

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Abstract
We have undertaken a theoretical study of the effect of magnetoelastic interactions on ferromagnetic resonance in thin films as a possible mechanism for an appreciable anisotropy in resonance linewidth. This study is based on a formalism developed by Tiersten, which is exact within the framework of the quasistatic approximation. The resonance frequency and linewidth are calculated from the simultaneous solution of the coupled magnetoelastic equations of motion under various magnetic and elastic boundary conditions. We find that the magnetoelasticity has an appreciable effect on the resonance linewidth only in the cases where an elastic wave undergoes a thickness resonance near the ferromagnetic-resonance frequency, which we call the "ferromagnetoelastic resonance condition." The above facts have made it possible to develop a self-consistent approximate method, which greatly simplifies the mathematical treatment without sacrificing the physical model. The agreement between the approximate and exact calculations is excellent.