Emergent magnetic states due to stacking and strain in the van der Waals magnetic trilayer CrI3

Recently, three different magnetic states were observed experimentally in trilayer CrI3 under pressure, including ferromagnetic (FM)-↑↑↑, FM-↓↑↓, and FM-↑↑↓. To reveal the nature of the three observed magnetic states, we studied the magnetic properties of four possible stacking structures in trilayer CrI3: Structures I (rhombohedral), II (monoclinic), III (hexagonal), and IV (triclinic). We find that all four stacking structures possess the FM-↑↑↑ ground state. After applying a few strains, FM-↓↑↓ becomes the ground state in structures II and III, and FM-↑↑↓ is preferred in structure IV, while FM-↑↑↑ persists in structure I. Our results unveil that the three magnetic states observed in trilayer CrI3 may correspond to different stacking structures with small tensile strains, which can well interpret the experimentally obtained pressure-dependent interlayer coupling and Curie temperature. Our present study paves a way to design magnetic multilayers with required magnetic states by tuning stacking and strain.