Observation of spontaneous x-ray magnetic circular dichroism in a chiral antiferromagnet

TL;DR

This paper reports the first observation of spontaneous x-ray magnetic circular dichroism in a chiral antiferromagnet, Mn$_{3}$Sn, confirming theoretical predictions about its origin from inverse triangular spin structures.

Contribution

It provides experimental evidence of spontaneous XMCD in a chiral antiferromagnet, linking it to the inverse triangular spin structure and magnetic octupole polarization.

Findings

Spontaneous XMCD observed in Mn$_{3}$Sn thin films.

XMCD signals originate from inverse triangular spin structure.

Results align with recent theoretical predictions.

Abstract

X-ray magnetic circular dichroism (XMCD) signals are usually absent in antiferromagnets. In this letter, we report the observation of spontaneous XMCD spectra originating from the inverse triangular spin structure, or the polarization of the cluster magnetic octupole, in the chiral antiferromagnet Mn$_{3}$Sn thin film. The result is consistent with the recent theoretical predictions that the inverse triangular spin structure can give rise to finite XMCD signals in the absence of net magnetization [J. Phys. Soc. Jpn. 89, 083703 (2020) and Phys. Rev. Lett. 126, 157402 (2021)].