Curvature-Induced Magnon Frequency Combs

TL;DR

This paper demonstrates that geometric curvature in ferromagnetic thin films can generate tunable magnon frequency combs through nonlinear three-magnon scattering, without the need for complex spin textures, revealing new control methods for magnonic devices.

Contribution

It introduces a novel geometric approach to generate magnon frequency combs using curvature-induced effects, bypassing the need for topological spin textures.

Findings

Curvature transforms ferromagnetic resonance into localized magnon bound states.

Curvature-driven processes produce equally spaced magnon frequency combs.

Simulation confirms curvature effects enable control of magnon interactions.

Abstract

Generating magnon frequency combs (MFCs) with tunable spacing via a single-frequency driving is crucial for practical applications but it typically relies on complex spin textures like skyrmions or vortices. Here, we theoretically and numerically demonstrate MFC generation in geometrically curved ferromagnetic thin films using single-frequency microwave excitation, without topological spin textures. We first show that the curvature transforms the planar ferromagnetic resonance into a localized, redshifted magnon bound state, which, under non-resonant driving, activates sequential three-magnon scattering processes assisted by the curvature-driven effective anisotropy and Dzyaloshinskii-Moriya interaction. It finally produces equally spaced, robust frequency combs with spacing exactly set by the bound mode frequency. Moreover, we find that the curvature gradient at the hybrid interface mimics an analog event horizon, with the bound state's redshift resembling gravitational effects in black hole physics. Micromagnetic simulations confirm these curvature-driven nonlinear phenomenon, unveiling a novel geometric strategy for controlling magnon interactions and advancing compact magnonic devices.