Spin wave excitation and propagation in ultra-thin nm-thick yttrium iron garnet films*

Magnonics has received increasing attention over the past decades, and it is widely considered to open up new opportunities to transport information by using spin waves (SWs) without charge currents. In our paper, we investigate experimentally the excitation and propagation of SW in 7-nm thick yttrium iron garnet (YIG) thin films with an ultra-low damping constant. On the top of YIG, conventional coplanar waveguides are integrated to excite a large series of short-wavelength spin waves (SWs). The scattering parameters are measured by using a vector network analyzer, which give access to observe the transmission of SW in the films. Consequently, by utilizing the experimental results, we calculate and extract the group velocity as well as the dispersion relation of SWs. Our work may be useful for providing the basis for SW logic devices at GHz rates with low power consumption.