Magnetoelastic coupling enhancement induced by a phonon channel in multiferroic composites

Enhancing the nonconservative force exerted on the ferromagnetic material is a key strategy for improving magnetoelastic coupling in multiferroic composites. Inspired by the mechanism of pulsed lasers injecting phonons directly into ferromagnetic materials, we propose a method to introduce and amplify phonons by constructing a “phonon channel”. Analyzing the magnon excitation spectrum reveals that magnetoelastic coupling is significantly enhanced with an increasing amplification coefficient Ap of nonconservative force in the phonon channel. When the external magnetic field is parallel to the wave vector of the spin wave, the amplitude of magnons in the anti-crossing region exhibits left-right symmetry with respect to the crossing point. In contrast, when the magnetic field is perpendicular, the symmetry becomes up-down. Introducing a coupling layer into the multiferroic composites provides a viable approach to realizing the phonon channel. Taking a multiferroic composite structure consisting of polyvinylidene fluoride and yttrium iron garnet as an example, we compare the electrical and acoustic properties of multiferroic composites with and without a coupling layer in the microwave frequency band. The enhancement of electrical and acoustic properties confirms the effectiveness of the phonon channel in multiferroic composites.