Proposal of Film-penetrating Transducers for a Spin-wave Reservoir Computing Chip

We propose a spin-wave antenna structure that penetrates a garnet film, which we named film-penetrating transducers (FPTs). FPTs possess a zero-dimensional feature that allows flexible placements and sufficient numbers of input/output electrodes for spin-wave reservoir computing. We first explain the structure and operation of FPTs. Then, we numerically construct and analyze a basic spin-wave reservoir chip model. We obtain intricate patterns of spin-wave propagation and interference that reflect the high dimensionality of the system. We also demonstrate the nonlinearity of the output electrical signal from an FPT detector of the system. Our results strongly suggest that FPTs preserve the important properties of a physical reservoir while ensuring large degrees of freedom for both the arrangements and amounts of spin-wave exciters and detectors.