Direct imaging Berry curvature-induced transport and domain behavior in noncollinear single-crystal antiferromagnetic thin films.

The discovery of the intrinsic anomalous Hall effect (AHE) in noncollinear antiferromagnets has opened a plethora of promising opportunities in antiferromagnetic devices. The key challenges limiting their full potential are (i) high-quality epitaxial thin-film growth and (ii) the understanding of Berry curvature and antiferromagnetic domain physics. Here, we focus on a noncollinear antiperovskite antiferromagnet Mn3NiN as a model system, successfully grown as a single-crystal epitaxial thin film. Combining multiple experiments supported by theoretical calculations, we probe the Berry curvature associated with antiferromagnetic Γ4g domains in Mn3NiN and its strong connection to an AHE. We directly image the antiferromagnetic domains driving the intrinsic Berry curvature with high-resolution Sagnac MOKE (magneto-optical Kerr-effect) microscopy, controlling spatial distribution and dynamics by varying temperature and applied magnetic fields. Our findings provide critical advancement of the fundamental understanding and wide tunability of Berry curvature in noncollinear antiferromagnets important for realization in potential spintronic applications.