Band gap control in periodic structure with magnonic crystal and ferroelectric

At present, magnonic crystals (MC), which are micron- or submicron- scale periodic structures formed on the surface of ferromagnetic films (FF), are of great interest to the researchers. The presence of a spatial period results in formation of band gaps in the spectrum of the magnetostatic waves (MSW) propagating in these structures for the wave numbers that satisfy the Bragg resonance condition The appealing feature of the magnonic crystals is that it is possible to control their band gaps with an external magnetic field and to develop tunable devices for microwave frequency data processing. In improving the band gap-control functional capabilities of the MCs, it is of interest to investigate layered multiferroid structures composed of MC on basis ferromagnetic film and ferroelectric (FE). At high values of the dielectric permittivity, which depends on the applied constant electric field, the electromagnetic waves (EMW) in the FE are substantially slowed down. In this case, as it is known, in the FF-FE structure, at frequencies close to the frequency of the phase synchronism between the EMW and MSW, hybrid electromagnetic-spin waves (HEMSW) arise. The values of the phase synchronism frequencies are determined by both the electric and magnetic fields, i.e., a dual control of the characteristics of the HEMSWs excited in these layered structures is possible. This report presents the results of investigation of the mechanisms of formation and control capabilities band gaps in the structure MC-FE. The main distinctions of the band gaps in this structure from those in a single MC have been determined. It is shown that the characteristics of these band gaps can be controlled by the electric and magnetic field.