Magnetostatic waves and spin waves in layered ferrite structures

Abstract

Collective magnetic excitations are supported by multiple ferrite layers. The character of magnetostatic waves is calculated for such systems and is illustrated for three different layers variously spaced (accurate control of the delay characteristics is shown to be possible) as well as for very many similar layers equally spaced. For volume waves on many layers, collective spin-wave-like modes of long wavelength form a continuum that evolves smoothly into narrow bands characteristic of the layers at short wavelength. For surface waves, an excitation similar to the surface wave on a continuous medium appears when the spacing is less than the layer thickness, but a dense continuum of other excitations (not analogous to those of a uniform medium) always persists even for small spacings. This unexpected spectrum is related to a novel system of modes localized on the gaps.