Observation of domain wall in chiral antiferromagnet Mn₃Sn realized perpendicular magnetization

Magnetic domain wall in chiral antiferromagnet is an important factor in developing fast magnetic memory. The fast speed of the domain wall driven by the current guarantees the perpendicular magnetic memory to move fast, but the domain wall structure, the physics background, has yet to be revealed. Here, we observed the domain wall between perpendicular magnetization of cluster magnetic octupole in Mn₃Sn. Magnetic domains with over hundreds nm scale are observed using nanoscale scanning diamond magnetometry. Reconstructed magnetization is the most consistent with perpendicular polarization in all axes, including the tilted. The domain wall dominated by exchange interaction, not grain boundary, tells us the physical properties and the domain wall chirality. The magnetization axis in the domain wall rotates in the Kagome plane, which suggests that the magnetic octupole is preserved in the domain wall. The estimated domain wall width is much shorter than that of the bulk crystal. Detailed observation of the domain wall powerfully assists in developing materials and devices. Simultaneous revealing of the physical background contributes to understanding the non-trivial domain and spin structure.