Interplay between nonlinear spectral shift and nonlinear damping of spin waves in ultrathin YIG waveguides

TL;DR

This study investigates how nonlinear effects influence the wavelength and damping of spin waves in ultrathin YIG waveguides, revealing controllable wavelength shifts and damping behaviors critical for spin-wave device optimization.

Contribution

It provides direct phase-resolved imaging of nonlinear wavelength modifications and damping effects in ultrathin YIG waveguides at moderate microwave powers.

Findings

Nonlinear wavelength variation up to 18% observed.

Strong spatial dependence of wavelength due to nonlinear damping.

Wavelength controllability by microwave power demonstrated.

Abstract

We use the phase-resolved imaging to directly study the nonlinear modification of the wavelength of spin waves propagating in 100-nm thick, in-plane magnetized YIG waveguides. We show that, by using moderate microwave powers, one can realize spin waves with large amplitudes corresponding to precession angles in excess of 10 degrees and nonlinear wavelength variation of up to 18 percent in this system. We also find that, at large precession angles, the propagation of spin waves is strongly affected by the onset of nonlinear damping, which results in a strong spatial dependence of the wavelength. This effect leads to a spatially dependent controllability of the wavelength by the microwave power. Furthermore, it leads to the saturation of nonlinear spectral shift's effects several micrometers away from the excitation point. These findings are important for the development of nonlinear, integrated spin-wave signal processing devices and can be used to optimize their characteristics.