Multiple antiferromagnetic phases and magnetic anisotropy in exfoliated CrBr₃ multilayers

In twisted two-dimensional (2D) magnets, the stacking dependence of the magnetic exchange interaction can lead to regions of ferromagnetic and antiferromagnetic interlayer order, separated by non-collinear, skyrmion-like spin textures. Recent experimental searches for these textures have focused on CrI₃, known to exhibit either ferromagnetic or antiferromagnetic interlayer order, depending on layer stacking. However, the very strong uniaxial anisotropy of CrI₃ disfavors smooth non-collinear phases in twisted bilayers. Here, we report the experimental observation of three distinct magnetic phases-one ferromagnetic and two antiferromagnetic-in exfoliated CrBr₃ multilayers, and reveal that the uniaxial anisotropy is significantly smaller than in CrI₃. These results are obtained by magnetoconductance measurements on CrBr₃ tunnel barriers and Raman spectroscopy, in conjunction with density functional theory calculations, which enable us to identify the stackings responsible for the different interlayer magnetic couplings. The detection of all locally stable magnetic states predicted to exist in CrBr₃ and the excellent agreement found between theory and experiments, provide complete information on the stacking-dependent interlayer exchange energy and establish twisted bilayer CrBr₃ as an ideal system to deterministically create non-collinear magnetic phases.