Linear and parametric phonon-magnon interactions in hybrid magnetoacoustic resonator

Abstract

We present experimental and theoretical studies of linear and parametric spin wave resonant excitation accompanied by spin currents (spin pumping) in a hybrid multifrequency bulk acoustic wave resonator, consisting of a ZnO piezoelectric transducer, yttrium iron garnet (YIG) films on a gallium gadolinium garnet substrate, and a heavy metal Pt layer. Acoustic resonant modes electrically excited by the transducer drive the magnetization dynamics in YIG—acoustic spin waves, which, in turn, create a spin pumping from YIG into Pt detected there via the inverse spin Hall effect (ISHE). Spin waves and spin pumping are studied by simultaneous frequency-field mapping of the ISHE voltage and the acoustic resonator spectra at the external magnetic field. Comparison of these characteristics with theoretical calculations allows us to determine the frequency-field regions of both linear and parametric acoustic spin wave excitation, as well as threshold powers. The combination of the sensitive acoustic resonator spectroscopy technique with the electrical detection of magnetic dynamics by the ISHE proved to be an effective method for spin waves’ dispersion and damping, and material parameter study.