Nonlinear mode conversion in monodomain magnetic squares

TL;DR

This study investigates how strong microwave excitation causes nonlinear mode conversion in magnetic squares, revealing the role of nonlinear damping in generating long-wavelength harmonics through experimental and theoretical analysis.

Contribution

It demonstrates the nonlinear generation of spin-wave harmonics in magnetic squares and highlights the influence of nonlinear damping, supported by experimental data and Ginzburg-Landau modeling.

Findings

Nonlinear generation of long-wavelength harmonics observed.

Nonlinear damping is the main governing factor.

Experimental and theoretical results are consistent.

Abstract

Modifications of spatial distributions of dynamic magnetization corresponding to spinwave eigenmodes of magnetic squares subjected to a strong microwave excitation field have been studied experimentally and theoretically. We show that an increase of the excitation power leads to a nonlinear generation of long-wavelength spatial harmonics caused by the nonlinear cross coupling between the eigenmodes. The analysis of the experimental data shows that this process is mainly governed by the action of the nonlinear spin-wave damping. This conclusion is further supported by the numerical calculations based on the complex Ginzburg-Landau equation phenomenologically taking into account the nonlinear damping.