Large anomalous Hall effect in L12-ordered antiferromagnetic Mn3Ir thin films

Abstract

Antiferromagnets having negligible net magnetization but a topologically nontrivial spin structure are a good testbed for investigating the intrinsic anomalous Hall effect (AHE). In this Letter, we explore L12-ordered Mn3Ir thin films, which are one of the noncollinear antiferromagnets predicted to exhibit the intrinsic AHE due to their topologically nontrivial spin structure. The anomalous Hall conductivity as large as σAHE = 40 Ω−1 cm−1 was observed at R.T. This value can be translated to the anomalous Hall conductivity per net magnetization M as |σAHE/M| = 0.6 V−1, which is much larger compared to those for general ferromagnetic materials. We also show that σAHE depends on the crystallinity of Mn3Ir as well as the chemical order parameter S characterizing a content of the L12 phase. Our results experimentally verify that L12-ordered Mn3Ir thin films exhibit the topologically originated AHE.