Observation of chiral domain walls in an octupole-ordered antiferromagnet

TL;DR

This study visualizes chiral domain walls in an octupole-ordered antiferromagnet Mn3Sn using quantum magnetometry, revealing detailed magnetic textures and advancing understanding for spintronic applications.

Contribution

It provides the first direct nanoscale imaging of magnetic domains and domain walls in Mn3Sn, elucidating the octupole order and magnetic chirality.

Findings

Detected intrinsic magnetic domains and domain walls in Mn3Sn.

Quantified the polarization angle and chirality of domain walls.

Measured the width and local magnetization of domains.

Abstract

Spin chirality in antiferromagnets offers new opportunities for spintronics. The kagome antiferromagnet Mn3Sn is a paradigmatic material in which the antiferromagnetic order parameter can be detected and controlled by electrical means. However, direct investigation of the magnetic texture of Mn3Sn has been challenging because of the tiny moment hosted in its magnetic octupole, hindering further clarification of this unique material. Here, we address this issue by observing the stray magnetic field from Mn3Sn using a diamond quantum scanning magnetometer. The spatially-resolved intrinsic domains and domain walls in a high-quality single-crystalline Mn3Sn film quantitatively reveal the polarization angle of the magnetic octupole in the kagome plane, the domain's local magnetization, the domain wall's width and chirality, and the octupole order in domain walls. Our nanoscale investigation of Mn3Sn, a powerful complement to macroscopic measurements, paves the road for developing chiral antiferromagnetism and its potential for spintronic applications.