Mode-dependent magnonic noise

Abstract The performance of magnonic devices, such as converters, switches, and multiplexers, depends significantly on the magnonic noise. Although a peculiar discrete magnonic noise has been reported, concrete magnon dynamics under high-magnon density conditions have not been clarified. Therefore, this study performs zero-span measurements of the spectrum analyser to accurately detect magnonic noise as a fluctuation of the spin-wave amplitude. The results of low-frequency magnonic noise demonstrated spin-wave mode dependency, indicating the existence of a peculiar magnon surface state. Furthermore, the energy thresholds of four-magnon scattering and auto-oscillation were determined using magnonic white noise. We believe the noise data presented here can help promote and accelerate theoretical and experimental research on magnons.