Optical Probing of Wave Driven Magneto-acoustic Resonance

The resonant interaction of electrically excited traveling surface acoustic waves and magnetization has hitherto been probed through the acoustic component. In this work we investigated it using time-resolved magneto-optical detection of magnetization dynamics. To that end, we develop an experimental scheme where laser pulses are used both to generate the acoustic wave frequency and to probe magnetization dynamics, thus ensuring perfect phase locking. The light-polarization dependence of the signal enables us to disentangle elasto-optical and magneto-optical contributions and to obtain the in-plane and out-of-plane components of the magnetization dynamics. Magnetization precession is proven to be driven solely by the acoustic wave. Its amplitude is shown to resonate at the same field at which we detect piezoelectrically the resonant attenuation of the acoustic wave, clearly evidencing the magnetoacoustic resonance with high sensitivity.