Magnetic imaging of antiferromagnetic domain walls

TL;DR

This paper demonstrates the direct nanoscale magnetic imaging of antiferromagnetic domain walls in various materials using cryogenic magnetic force microscopy, revealing their structure and magnetic properties under different conditions.

Contribution

It introduces a method for visualizing antiferromagnetic domain walls with nanoscale resolution in magnetic fields, advancing understanding and control of spin textures in antiferromagnets.

Findings

Domain walls show higher magnetic susceptibility or net moments than domains.

Domain walls form randomly with thermal and magnetic field dependence.

Visualization aids exploration of phenomena and control in topological antiferromagnets.

Abstract

The control of domain walls or spin textures is crucial for spintronic applications of antiferromagnets. Despite many efforts, it has been challenging to directly visualize antiferromagnetic domains or domain walls with nanoscale resolution, especially in magnetic field. Here, we report magnetic imaging of domain walls in several uniaxial antiferromagnets, the topological insulator MnBi$_2$Te$_4$ family and the Dirac semimetal EuMnBi$_2$, using cryogenic magnetic force microscopy (MFM). Our MFM results reveal higher magnetic susceptibility or net moments inside the domain walls than in domains. Domain walls in these antiferromagnets form randomly with strong thermal and magnetic field dependences. The direct visualization of domain walls and domain structure in magnetic field will not only facilitate the exploration of intrinsic phenomena in topological antiferromagnets, but also open a new path toward control and manipulation of domain walls or spin textures in functional antiferromagnets.