Controlling the Nonlinear Relaxation of Quantized Propagating Magnons in Nanodevices

Area of Science:

• Condensed Matter Physics
• Spintronics
• Magnonics

Background:

• Linear magnetization dynamics are typically modeled using viscous Gilbert damping.
• Strong excitations introduce nonlinear damping processes, like magnon-magnon interactions, creating additional relaxation pathways.
• Understanding these nonlinear effects is crucial for advanced magnetic devices.

Purpose of the Study:

• To investigate nonlinear relaxation mechanisms of strongly driven propagating spin waves in yttrium iron garnet (YIG) nanoconduits.
• To explore the role of intermodal magnon scattering in the relaxation process.
• To demonstrate control over nonlinear dissipation through device quantization.

Main Methods:

• Utilized space- and time-resolved microfocused Brillouin light scattering (μFBIS) spectroscopy.
• Employed micromagnetic simulations to complement experimental observations.
• Investigated spin wave propagation in YIG nanoconduits with varying quantization levels.

Main Results:

• Observed that nonlinear magnon relaxation in quantized YIG nanoconduits exhibits intermodal scattering.
• Demonstrated that magnons scatter into higher-order quantized modes via a cascade of events.
• Showed that controlling magnon band quantization in single-mode devices can limit intermodal dissipation.

Conclusions:

• Nonlinear magnon relaxation in nanostructured YIG is dominated by intermodal scattering.
• Quantization engineering offers a pathway to control nonlinear damping in magnonic systems.
• Findings are vital for developing advanced spin-wave devices and realizing scaled magnonic Bose-Einstein condensates.