Anomalous Hall effect in noncollinear antiferromagnetic Mn3NiN thin films

We have studied the anomalous Hall effect (AHE) in strained thin films of the frustrated antiferromagnet Mn3NiN. The AHE does not follow the conventional relationships with magnetization or longitudinal conductivity and is enhanced relative to that expected from the magnetization in the antiferromagnetic state below T-N = 260K. This enhancement is consistent with origins from the noncollinear antiferromagnetic structure, as the latter is closely related to that found in Mn3Ir and Mn3Pt where a large AHE is induced by the Berry curvature. As the Berry-phase-induced AHE should scale with spin-orbit coupling, yet larger AHE may be found in other members of the chemically flexible Mn(3)AN structure.