Large anomalous Hall effect in a non-collinear antiferromagnet at room temperature

Anomalous anomalies in an antiferromagnet The Hall effect as it is commonly encountered describes the voltage difference that builds up across a conductor when an electric current flows in the presence of a magnetic field. For ferromagnetic materials, with built-in magnetism, a similar phenomenon — known as the anomalous Hall effect — is sometimes observed even in the absence of an external magnetic field. Such an effect would not normally be expected for antiferromagnets, which have no net magnetization in the zero-field state. Inspired by recent theoretical ideas concerning the detailed origins of the anomalous Hall effect, Satoru Nakatsuji et al. show that such a counterintuitive effect can be seen in the antiferromagnetic material Mn3Sn as a consequence of the unusual and complex arrangement of its constituent magnetic moments. The effect is not only large (comparable to that of ferromagnetic metals) but easily switchable with a small applied field — a combination of properties that might prove useful for spintronic applications.