Magnonics in ferromagnetic films

Abstract

In this chapter, we study spin waves in thin ferromagnetic films. Initially, we present the semiclassical theory of magnetostatic waves developed in the 1960s by Damon and Eshbach to explain microwave measurements in yttrium iron garnet bulk samples in the form of slabs. Later, with the development of techniques to fabricate thin films, the theory became the basis to study magnonic phenomena in these systems. Next, we present a quantum formulation of spin waves in thin films that applies to wave numbers from the magnetostatic to the exchange regions. The third topic is the spin wave relaxation by two-magnon scattering originating in the roughness of the surfaces and interfaces of ultrathin ferromagnetic films. Finally, we present a semiclassical calculation of the spin wave properties in coupled magnetic films.