Nonlinear losses in magnon transport due to four-magnon scattering

TL;DR

This study investigates how nonlinear four-magnon scattering affects magnon transport in CoFe waveguides, revealing that high excitation powers induce nonlinear effects that can distort damping measurements.

Contribution

It demonstrates the significance of nonlinear four-magnon scattering in magnon transport and emphasizes the need to operate in the linear regime for accurate damping parameter extraction.

Findings

Magnon propagation length decreases at high powers due to nonlinear scattering.

Nonlinear effects can lead to misinterpretation of damping parameters.

Maintaining linear regime is essential for accurate magnon transport measurements.

Abstract

We report on the impact of nonlinear four-magnon scattering on magnon transport in microstructured Co25Fe75 waveguides with low magnetic damping. We determine the magnon propagation length with microfocused Brillouin light scattering over a broad range of excitation powers and detect a decrease of the attenuation length at high powers. This is consistent with the onset of nonlinear four-magnon scattering. Hence, it is critical to stay in the linear regime, when deriving damping parameters from the magnon propagation length. Otherwise, the intrinsic nonlinearity of magnetization dynamics may lead to a misinterpretation of magnon propagation lengths and, thus, to incorrect values of the magnetic damping of the system.