Frequency Demultiplexing of Spin Waves by Inverse-designed Magnetization Patterns, Experimentally Realized by FIB Irradiation

We present the spatial separation of spin waves with distinct wavelengths when traveling through machine-learned magnetization landscapes, which can be used to demultiplex the corresponding excitation frequencies. Focused ion beam irradiation is used to modify the magnetization of YIG locally, and the maximum achievable magnetization change is used as a training basis to generate a binary 2D magnetization profile. The pattern is created with an inverse design approach using a micromagnetic solver embedded in the PyTorch framework. Subsequently, the magnetization pattern is experimentally realized using the corresponding FIB dose and its performance is demonstrated using time-resolved MOKE microscopy.