Direct observation of van der Waals stacking–dependent interlayer magnetism

Abstract

Stacking control Recent searches for two-dimensional magnets have turned up a number of related van der Waals materials, such as chromium triiodide (CrI 3 ) and chromium tribromide (CrBr 3 ). Although their properties are expected to be similar, in bilayer form, the former is antiferromagnetic, whereas the latter appears to be a ferromagnet. Chen et al. used spin-polarized scanning tunneling microscopy to determine that the nature of the magnetic state in bilayer CrBr 3 depends on the type of stacking of its monolayers. An antiferromagnetic state formed when the two monolayers were oriented in the same direction, whereas the opposite orientation led to ferromagnetism. Science , this issue p. 983