The anomalous Hall effect in non-collinear antiferromagnetic Mn${}_3$NiN thin films

Abstract

We have studied the anomalous Hall effect (AHE) in strained thin films of the frustrated antiferromagnet Mn${}_3$NiN. 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 $T_{\mathrm{N}}=260$\,K. This enhancement is consistent with origins from the non-collinear antiferromagnetic structure, as the latter is closely related to that found in Mn${}_3$Ir and Mn${}_3$Pt 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${}_{3}A$N structure.