Brillouin light scattering study of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al and Co$_{2}$FeAl Heusler compounds

TL;DR

This study uses Brillouin light scattering to analyze the magnonic spectra of two Heusler compounds, revealing their exchange constants and mode asymmetries, contributing to understanding their magnetic properties.

Contribution

It provides the first detailed BLS analysis of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al and Co$_{2}$FeAl, including quantitative exchange parameters and mode asymmetry explanations.

Findings

Exchange constant for CCFA is 0.48 μerg/cm.

Exchange constant for Co$_2$FeAl is 1.55 μerg/cm.

Asymmetry in BLS spectra explained by hybridized spin-wave modes.

Abstract

The thermal magnonic spectra of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al (CCFA) and Co$_2$FeAl were investigated using Brillouin light scattering spectroscopy (BLS). For CCFA, the exchange constant A (exchange stiffness D) is found to be 0.48 $\mu$erg/cm (203 meV A$^2$), while for Co$_2$FeAl the corresponding values of 1.55 $\mu$erg/cm (370 meV A$^2$) were found. The observed asymmetry in the BLS spectra between the Stokes and anti-Stokes frequencies was assigned to an interplay between the asymmetrical profiles of hybridized Damon-Esbach and perpendicular standing spin-wave modes, combined with the optical sensitivity of the BLS signal to the upper side of the CCFA or Co$_2$FeAl film.