Strain-mediated tunability of spin-wave spectra in the adjacent magnonic crystal stripes with piezoelectric layer

We demonstrate that properties of spin-wave propagation in the adjacent magnonic crystal stripes with one of them in contact with a piezoelectric layer can be controlled by an external electric field. We perform microwave spectroscopy and employ a theoretical approach based on the analysis of the set of coupled wave equations. By considering incident and reflected waves in the first Brillouin zone, we calculate the reflection coefficients of the magnonic structure. Two narrow magnon bands are observed in the experiment, and their behavior with the variation of the electric field applied to the piezoelectric layer was shown. The finite-element calculations of the self-consistent eigenvalue problem elucidate how the influence of the piezoelectric layer can be modeled as a localized strain-induced internal magnetic field and its variation affects the spin-wave dispersion. Both the frequency shift and closing of a magnon band are detected in our measurements and confirmed by the simulations and the analytical approach. Therefore, we demonstrate the electric field control of the magnonic bands. Our results reveal the mechanism of the spin-wave spectra control in the coupled magnonic crystals. The results pave the way for the implementation of frequency selective magnonic devices based on a straintronic approach.