Parametric pumping of coherent spin waves by surface acoustic waves

This study investigates the parametric pumping of coherent forward volume spin waves using traveling surface acoustic waves in thin-film yttrium iron garnet. Theoretical analysis, micromagnetic modeling, and experimental validation of the nonlinear three-wave mixing interaction are presented. The energy and momentum imparted by the acoustic pump enable frequency translation and angular deflection of the idler spin waves generated, providing a mechanism for the spectral and spatial separation of signals in magnonic devices. Experimental results demonstrate bilinear parametric interactions, frequency conversion, and angular separation of spin waves under degenerate and non-degenerate conditions and provide evidence of the possibility of parametric amplification of signal spin waves below the instability threshold for generation from the thermal background. The results align qualitatively with theoretical predictions and micromagnetic simulations and lay a path toward developing magnonic signal processing and computing devices utilizing acoustic parametric pumping of spin waves.