Chiral damping of magnons

TL;DR

This paper reports the first direct observation of chiral damping in magnons within chiral magnets using Brillouin light scattering, revealing odd symmetry in linewidths and introducing a new measurement methodology.

Contribution

It presents the first direct measurement of chiral damping, linking linewidth asymmetry to chiral effects, and introduces a novel BLS-based method for quantifying chiral damping.

Findings

Linewidths show odd symmetry with respect to magnon wave vector.

Chiral damping can be independently deduced from BLS spectrum analysis.

The study introduces a new methodology for quantifying chiral damping.

Abstract

Chiral magnets have garnered significant interest due to the emergence of unique phenomena prohibited in inversion-symmetric magnets. While the equilibrium characteristics of chiral magnets have been extensively explored through the Dzyaloshinskii-Moriya interaction (DMI), non-equilibrium properties like magnetic damping have received comparatively less attention. We present the inaugural direct observation of chiral damping through Brillouin light scattering (BLS) spectroscopy. Employing BLS spectrum analysis, we independently deduce the Dzyaloshinskii-Moriya interaction (DMI) and chiral damping, extracting them from the frequency shift and linewidth of the spectrum peak, respectively. The resulting linewidths exhibit clear odd symmetry with respect to the magnon wave vector, unambiguously confirming the presence of chiral damping. Our study introduces a novel methodology for quantifying chiral damping, with potential ramifications on diverse nonequilibrium phenomena within chiral magnets.