Helical spin dynamics in Cu$_2$OSeO$_3$ as measured with small-angle neutron scattering

TL;DR

This study uses small-angle neutron scattering to investigate the temperature-dependent spin wave excitations in Cu$_2$OSeO$_3$, revealing detailed magnetic properties and resolving previous discrepancies.

Contribution

It provides the first detailed temperature evolution of helimagnon excitations in Cu$_2$OSeO$_3$ using SWSANS, enhancing understanding of chiral magnet dynamics.

Findings

Temperature-dependent spin-wave stiffness measured

Damping constant evolution characterized

Results align with theoretical models

Abstract

The insulating chiral magnet Cu$_2$OSeO$_3$ exhibits a rich array of low-temperature magnetic phenomena, making it a prime candidate for the study of its spin dynamics. Using spin wave small-angle neutron scattering (SWSANS), we systematically investigated the temperature-dependent behavior of the helimagnon excitations in the field-polarized phase of Cu$_2$OSeO$_3$. Our measurements, spanning 5-55 K, reveal the temperature evolution of spin-wave stiffness and damping constant with unprecedented resolution, facilitated by the insulating nature of Cu$_2$OSeO$_3$. These findings align with theoretical predictions and resolve discrepancies observed in previous studies, emphasizing the enhanced sensitivity of the SWSANS method. The results provide deeper insights into the fundamental magnetic properties of Cu$_2$OSeO$_3$, contributing to a broader understanding of chiral magnets.