Efficient spin-wave excitation by surface acoustic waves in ultra-low damping YIG/ZnO-heterostructures

We demonstrate the efficient excitation of spin waves in the ultra-low magnetic damping material yttrium-iron-garnet (YIG) by surface acoustic waves (SAWs). To this end, we employ interdigital transducers fabricated on a piezoelectric zinc oxide (ZnO) thin film covering the YIG. This enables the excitation of coherent, propagating Rayleigh-type and Sezawa-type SAWs. We find that the ultralow magnetic damping of YIG is retained after the ZnO-deposition and we carry out a comprehensive investigation of the magnetoelastic interaction due to the different SAW modes as a function of the external magnetic field magnitude and orientation. By measuring the SAW attenuation our experiments reveal a highly anisotropic and non-reciprocal SAW-SW-interaction in agreement with our model caluclation, while demonstrating that low-damping magnons can be efficiently excited by SAWs.