Observing high-k magnons with Mie-resonance-enhanced Brillouin light scattering

TL;DR

This paper demonstrates that Mie-resonance-enhanced Brillouin light scattering enables the detection of high-momentum, nanoscale spin waves, significantly expanding the capabilities of BLS in magnonic research.

Contribution

The authors introduce a novel method using Mie resonances in dielectric nanoparticles to surpass the traditional BLS momentum detection limit for nanoscale spin waves.

Findings

Mie resonances extend BLS detection range for high-k magnons.

Method applicable to thermally and coherently excited spin waves.

Enhances BLS utility for nanoscale magnonic experiments.

Abstract

Magnonics is a prospective beyond CMOS technology which uses magnons, the quanta of spin waves, for low-power information processing. Many magnonic concepts and devices were recently demonstrated at macro- and microscale, and now these concepts need to be realized at nanoscale. Brillouin light scattering spectroscopy and microscopy (BLS) has become a standard technique for spin wave visualization and characterization, and enabled many pioneering magnonic experiments. However, due to its fundamental limit in maximum detectable magnon momentum, the conventional BLS cannot be used to detect nanoscale spin waves. Here we show that optically induced Mie resonances in dielectric nanoparticles can be used to extend the range of accessible spin wave wavevectors beyond the BLS fundamental limit. The method is universal and can be used in many magnonic experiments dealing with thermally excited as well as coherently excited high-momentum, short-wavelength spin waves. This discovery significantly extends the usability and relevance of the BLS technique for nanoscale magnonic research.