Magnetoelastic Waves in Thin Films

Abstract

This chapter discusses the physics of magnetoelasticity and magnetoelastic waves in thin films as well as their mathematical description. Magnetoelastic waves occur as a result of strong coupling between spin waves and elastic waves in magnetostrictive ferromagnetic media. In a first part, the basic behavior of spin waves is reviewed in both bulk ferromagnets as well as in thin films. Next, elastic waves are discussed with a focus on thin films. Then, the interactions between the elastic and magnetic domains are described and it is shown how this results in the formation of magnetoelastic waves. The description and the mathematical formalism of magnetoelastic waves in infinitesimally thin films is extended to magnetoelastic waves in thin films with finite thickness. The dispersion relations and eigenstates are derived and graphically visualised for such magnetoelastic waves. It is shown that the behavior strongly depends on the geometry of the system, especially on the polarization of the spin and elastic waves and the direction of the magnetization of the magnetostrictive ferromagnetic medium.