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.

No abstract

No abstract

The sulfoneamidohelicene tetramer in solution exhibits different molecular responses to the same cooling stimulus delivered once and twice under thermal hysteresis conditions. Its random-coil state at a high temperature was cooled and maintained at a given temperature for which its molecules remained in a random coil (first cooling); the resulting solution was heated and cooled, after which a helix dimer formed (second cooling). Such a property can be regarded as a molecular function of counting the numbers 1 and 2.

No abstract