RESUMO
In this paper, we discuss a new moiré system where the long moiré periodicity emerges from two dissimilar van der Waals layers with vastly different lattice constants. We reconstruct the first layer using a 3 by 3 supercell resembling the Kekulé distortion in graphene, and such reconstruction becomes nearly commensurate with the second layer. We term this construction a Kekulé moiré superlattice, which enables coupling between moiré bands from remote valleys in momentum space. Kekulé moiré superlattices can be realized in heterostructures of transition metal dichalcogenides and metal phosphorus trichalcogenides such as MoTe2/MnPSe3. By first-principles calculations, we demonstrate that the antiferromagnetic MnPSe3 strongly couples the otherwise degenerate Kramers' valleys of MoTe2, resulting in valley pseudospin textures that depend on the Néel vector direction, stacking geometry, and external fields. With one hole per moiré supercell, the system becomes a Chern insulator with highly tunable topological phases.
RESUMO
Moiré superlattices of twisted nonmagnetic two-dimensional (2D) materials are highly controllable platforms for the engineering of exotic correlated and topological states. Here, we report emerging magnetic textures in small-angle twisted 2D magnet chromium triiodide (CrI3). Using single-spin quantum magnetometry, we directly visualized nanoscale magnetic domains and periodic patterns, a signature of moiré magnetism, and measured domain size and magnetization. In twisted bilayer CrI3, we observed the coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) domains with disorder-like spatial patterns. In twisted double-trilayer CrI3, AFM and FM domains with periodic patterns appear, which is in good agreement with the calculated spatial magnetic structures that arise from the local stacking-dependent interlayer exchange interactions in CrI3 moiré superlattices. Our results highlight magnetic moiré superlattices as a platform for exploring nanomagnetism.