Spatially-extended nonlinear generation of short-wavelength spin waves in YIG nanowaveguides

TL;DR

This paper demonstrates nonlinear spin wave generation in YIG nanowaveguides, enabling the creation of short-wavelength waves through four-magnon interactions with low energy thresholds, useful for magnonic devices.

Contribution

It introduces a method to generate short-wavelength spin waves via engineered dispersion and nonlinear interactions in YIG nanowaveguides, expanding capabilities for magnonic applications.

Findings

Efficient four-magnon interactions over a wide wavelength range.

Generation of short-wavelength spin waves not directly excitable linearly.

Continuous energy transfer compensates propagation losses.

Abstract

We experimentally study nonlinear propagation of spin waves in microscopic yttrium iron garnet waveguides, where the dispersion spectrum is engineered to enable efficient four-magnon interactions over a wide range of wavelengths. We show that under these conditions, the initial monochromatic spin wave nonlinearly generates co-propagating spin waves with well-defined, discrete frequencies. This process is characterized by a low energy threshold and can be observed in a wide range of frequencies and excitation powers. Thanks to the engineered dispersion, the process allows the generation of waves with short wavelengths that cannot be excited directly by a linear excitation mechanism. The nonlinearly generated short-wavelength spin waves continuously acquire the energy from the initial pump wave during co-propagation, which results in compensation of their propagation losses over significant distances. The observed phenomena can be used to implement frequency- and wavelength-conversion operations in magnonic nanodevices and circuits.