(a) Schematic of the analyzed microscopic spin-wave waveguide, in this study assumed to be made from a thin layer of permalloy (Py, Ni81Fe19) in contact with Pt, and the coplanar waveguide (CPW) acting as spin-wave excitation source. (b) Schematic of the uni-directional emission: The interfacial Dzyaloshinskii-Moriya interaction splits the spin-wave dispersion (dashed lines) of waves running to the left and waves running to the right. In combination with the periodicity of the excitation spectrum by the coplanar waveguide (solid lines), this can be used to achieve an efficient spin-wave emission in only one propagation direction at a desired operation frequency (dashed vertical line).
