Coexistence Of Bloch And Neel Walls In A Collinear Antiferromagnet

We resolve the domain-wall structure of the model antiferromagnet Cr2O3 using nanoscale scanning diamond magnetometry and second-harmonic-generation microscopy. We find that the 180 degrees domain walls are predominantly Bloch-like, and can coexist with Neel walls in crystals with significant in-plane anisotropy. In the latter case, Neel walls that run perpendicular to a magnetic easy axis acquire a well-defined chirality. We further report quantitative measurement of the domain-wall width and surface magnetization. Our results provide fundamental input and an experimental methodology for the understanding of domain walls in pure, intrinsic antiferromagnets, which is relevant to achieve electrical control of domain-wall motion in antiferromagnetic compounds.