Interaction of Ultrasonic Waves with Thin Magnetic Films
Abstract
We discuss the interaction of an externally generated ultrasonic wave with a thin magnetic film, and the generation of phonons by driving such a film with a microwave field. Several geometries are considered. If the frequency of the driving wave is close to one of the spinwave resonance frequencies of the film, we exhibit an exact solution to the phonon equation of motion in the presence of onemagnononephonon terms in the magnetoelastic coupling. Some difficulties present in an earlier theory are eliminated. We find a contribution to the spin wave resonance linewidths from the onemagnononephonon terms. For the n=0 term of a Ni film, we estimate the magnetoelastic coupling may make a contribution to the linewidth of roughly ten percent of the total linewidth. If we denote this contribution to the linewidth by Γ_{n}^{(pn)} and the total linewidth by Γ_{n}, then we show that study of the interaction of an externally generated ultrasonic wave with the film provides a direct measure of the ratio Γ_{n}^{(pn)}Γ_{n}. The presence of a poor acoustical impedance match at a film surface is shown to introduce a factor in the expression for Γ_{n}^{(pn)} periodic in the external magnetic field, for a film of fixed thickness.
 Publication:

Physical Review
 Pub Date:
 May 1967
 DOI:
 10.1103/PhysRev.157.369
 Bibcode:
 1967PhRv..157..369M