Chiral Excitation of Exchange Spin Waves Using Gold Nanowire Grating

We propose an experimental method for the unidirectional excitation of spin waves. By structuring Au nanowire arrays within a coplanar waveguide onto a thin yttrium iron garnet (YIG) film, we observe a chiral coupling between the excitation field geometry of the nanowire grating and several well-resolved propagating magnon modes. We report a propagating spin wave spectroscopy study with unprecedented spectral definition, wavelengths down to 130nm and attenuation lengths well above 100 mu m over the 20GHz frequency band. The proposed experiment paves the way for future non-reciprocal magnonic devices.