Moiré skyrmions and chiral magnetic phases in twisted van der Waals magnets

Twisted van der Waals (vdW) magnets such as CrI3 have emerged as a unique platform to tune the properties of moiré superlattices. In particular, stacking dependent exchange that is prevalent in these materials can lead to new and unexpected phases as a function of twist angle. I will present a comprehensive theory of the magnetic phases in twisted vdW magnets through a combination of first-principles calculations and atomistic simulations. I will show that a wide range of noncollinear magnetic phases can be stabilized as a function of the twist angle and Dzyaloshinskii–Moriya interaction as a result of the competing interlayer antiferromagnetic coupling and the energy cost for forming domain walls. In particular, I will demonstrate that for small twist angles various skyrmion crystal phases can be stabilized in both CrI3 and CrBr3. These results provide an interpretation for the recent observation of noncollinear magnetic phases in twisted bilayer CrI3 and demonstrate the possibility of engineering further nontrivial magnetic ground states in twisted vdW magnets[1,2].