Influence of adjacent metal films on magnon propagation in Y3Fe5O12

Abstract

We studied a mechanism of magnon absorption from a magnon waveguide to adjacent metals. Magnon propagation in the yttrium-iron-garnet magnon waveguide induced/detected via coplanar waveguides was reduced by attaching metals to the magnon waveguide. In particular, the propagating magnon at the surface of the magnon waveguide was largely suppressed by attaching metal strips whereas the uniform or volume mode showed only a very slight decrease. A systematic study on the reduction of magnon propagation was performed by changing the material of metals, changing their thickness, and inserting $\mathrm{Si}{\mathrm{O}}_{2}$ between the magnon waveguide and metals. The reduction in magnon propagation by $\mathrm{Si}{\mathrm{O}}_{2}$ insertion indicated that the eddy-current contribution played a key role in magnon propagation with the magnon gate system with metal electrodes. Our study revealed the relationship between the magnon loss and metallic electrodes, which is indispensable in the fabrication of magnonic devices.