Goos-Hänchen effect of spin waves at heterochiral interfaces

<p class="MsoNormal">One of the most robust methods for measuring the Dzyaloshinskii-Moriya interaction (DMI) is the Brillouin light scattering spectroscopy (BLS) at present. But measuring the DMI parameter in a narrow magnetic strip is always a difficult problem because of the big laser spot size subjected to the diffraction limit of lights. In previous work, we proposed a nonlocal scheme to measure the DMI in a narrow magnetic strip by three-magnon processes, but it is only feasible for the magnetic strip with the width in the range of 50–100 nm. In this work, we observe a Goos-Hänchen shift of spin waves at the heterochiral interface when the spin-wave beam is totally reflected. We further explore the GH shift of spin waves by narrow DMI strips of different widths. It is found that the induced shift is independent of the strip width down to 10 nm, offering an approach to measure the DMI strength of ultranarrow magnetic strips of sub-50-nm scales. Our findings are helpful to understand the GH effect in chiral magnets and enable us to measure the DMI for ultranarrow magnetic strips via the magnonic GH shift, which fills in the gap of current technology.</p>