A detailed look into 2D magnetism

Abstract

Magnetism The van der Waals material chromium triiodide (CrI3) is a ferromagnet in the bulk but appears to become antiferromagnetic when thinned to a few atomic layers. Thiel et al. used a local magnetometry technique based on diamond nitrogen-vacancy centers to study the magnetism of these thin films at the nanoscale (see the Perspective by Fernandez-Rossier). In agreement with previous results, films with odd numbers of layers had magnetization values consistent with that of a single layer, indicating antiferromagnetic coupling. But when the researchers' probe caused an accidental puncture, the magnetization of a nine-layer film increased approximately ninefold to a value expected in a ferromagnetic material. Further characterization suggested that the puncture had caused a structural transition, linking the structural and magnetic properties of this enigmatic system. Science , this issue p. [973][1]; see also p. [935][2] [1]: /lookup/doi/10.1126/science.aav6926 [2]: /lookup/doi/10.1126/science.aax6598