Spin-wave diagnostics of ultrathin ferrite films

Abstract

A method of nondestructive control of the layered structure of submicron ferrite films comparable to the thickness of the transition (diffusion) layer at the film-substrate interface was proposed. The control technique was based on measurements of spin-wave resonance frequencies and mathematical processing of the measurement results. It was found that the inhomogeneity of magnetization in the transition layer provides the condition of phase synchronism of electromagnetic waves (photons) and exchange spin waves (magnons). In the region of the synchronism points, the effects of hybridization of coupled waves appeared. In this case, hybrid quasi-spin and quasi-electromagnetic waves were excited in the film. The quasi-spin wave at the film-substrate interface had a purely electromagnetic character, which ensured a good matching with the external microwave tract. Near the plane of phase synchronism, there was an intensive redistribution of energy in favor of increasing the power of the quasi-spin wave. At the same time, the excitation region of the spin-wave resonance significantly narrowed. The proposed mechanism of photon-magnon conversion is applicable to any ferrite-dielectric structures with a boundary diffusion layer, and can be useful in the development of superminiature controlled devices for analog processing of microwave information signals.