Electromagnonic crystals based on ferrite–ferroelectric–ferrite multilayers

In recent years, the microwave processes in artificial multiferroic media such as electromagnonic crystals have attracted increased research interest due to their potential applications for voltage-controlled spintronic devices. In contrast to the conventional magnonic crystals, the artificially created periodic structures are characterised by electrically and magnetically tunable band gaps in the wave spectrum where the propagation of the electromagnons is forbidden. In this study, an experimental realisation of an electromagnonic crystal based on a ferrite–ferroelectric–ferrite multilayer has been proposed. The authors have demonstrated for the first time a band-gap splitting, which arises from an interaction of three fundamental modes of two ferrite films separated by a ferroelectric layer. This splitting manifested itself as an additional stop-band appearance in the frequency response of the electromagnonic crystal. The obtained band structures are confirmed by numerical modelling using the coupled-mode approach and the transfer-matrix method. The authors expect that their results allow exploiting the electromagnonic crystal for enhanced logic control as well as for tunable microwave devices.