Resonant Nonlinear Damping of Quantized Spin Waves in Ferromagnetic Nanowires

TL;DR

This study investigates how geometric confinement in permalloy nanowires influences the damping of quantized spin waves, revealing a resonant nonlinear damping mechanism linked to three-magnon processes.

Contribution

It demonstrates the field-dependent resonant nonlinear damping of quantized spin waves in nanowires due to three-magnon confluence processes, a novel insight into spin wave dynamics.

Findings

Damping depends on magnetic field with a maximum at a specific bias field.

Resonant nonlinear damping is caused by three-magnon confluence processes.

Damping behavior varies with nanowire width and magnetic field.

Abstract

We use spin torque ferromagnetic resonance to measure the spectral properties of dipole-exchange spin waves in permalloy nanowires. Our measurements reveal that geometric confinement has a profound effect on the damping of spin waves in the nanowire geometry. The damping parameter of the lowest-energy quantized spin wave mode depends on applied magnetic field in a resonant way and exhibits a maximum at a field that increases with decreasing nanowire width. This enhancement of damping originates from a nonlinear resonant three-magnon confluence process allowed at a particular bias field value determined by quantization of the spin wave spectrum in the nanowire geometry.