Static and dynamic topological defects in the domain textures in the helical antiferromagnet Ni₂CoTeO₆

Real-space Bragg coherent x-ray diffractive imaging unveils the formation of bubble and stripe antiferromagnetic (AFM) phase domains on the surface of Ni₂CoTeO₆ single crystal. The stripe domains exhibit dislocation-type topological defects. The defects typically form as defect-antidefect pairs and can be created or annihilated by temperature changes and local heating. Near the Néel temperature, indications of a non-periodic stripe state with orientational order are found, and thermal fluctuations of the AFM domain walls are observed. Topological defect pairs dynamically form and disappear in the fluctuating state. These observations provide a real-space perspective on the dynamics of the AFM phase transition in a helical antiferromagnet. The remarkable tunability of AFM domain walls in a helical antiferromagnet underscores their potential for AFM spintronics applications.