Optimizing propagating spin wave spectroscopy

The frequency difference between two oppositely propagating spin waves can be used to probe several interesting magnetic properties, such as the Dzyaloshinskii-Moriya interaction (DMI). Propagating spin wave spectroscopy is a technique that is very sensitive to this frequency difference. Here, we show several elements that are important to optimize devices for such a measurement. We demonstrate that for wide magnetic strips, there is a need for de-embedding. Additionally, for these wide strips, there is a large parasitic antenna-antenna coupling that obfuscates any spin wave transmission signal, which is remedied by moving to smaller strips. The conventional antenna design excites spin waves with two different wave vectors. As the magnetic layers become thinner, the resulting resonances move closer together and become very difficult to disentangle. In the last part, we therefore propose and verify an alternative antenna design that excites spin waves with only one wave vector. We suggest to use this antenna design to quantify the DMI in thin magnetic layers.