Constructing 2D moiré and chiral materials

Misalignment-induced moiré patterns and chirality in two-dimensional materials offer vast opportunities for manipulating their properties, but they face challenges in synthesis and structural control.

Two-dimensional (2D) materials, despite their small thickness, can display chirality that enables prominent asymmetric optical, electrical transport, and magnetic properties. This Perspective discusses the intriguing physics enabled by the structural chirality and the possible ways to create and control chirality in 2D materials.

By means of a precise folding–tearing process, screw dislocations with helical cores — appearing in pairs and taking on a DNA-like double-helix structure — are engineered to control the growth of twisted bilayer graphene.

An alloy engineering approach is developed to reliably grow atomically thin bilayers with predictable and tunable moiré patterns.

The atomic reconstruction and stacking arrangement in twisted trilayer graphene with a range of varying twist angles are elucidated by four-dimensional scanning transmission electron microscopy, revealing the hierarchical moiré of moiré superstructures that govern the structural symmetry at different length scales.

Multiwalled WS₂ and WSe₂ nanotubes with predominantly a single chiral angle are produced in a chemical vapour deposition reactor using gold nanoparticles as a catalyst. This strategy paves the way for the growth of transition metal dichalcogenide nanotubes with controllable structures for further exploring their physical properties and potential applications.

A graphene origami–kirigami technique offers an approach for growing intertwined graphene spirals with fixed twist angles, enabling the chirality of one-dimensional wrinkles to be converted into the twist angle of vertically stacked two-dimensional layers.

Controlling the periodicity of synthesized moiré materials is vital to harness their unique physics. Here the authors realize the van der Waals epitaxy of tunable moiré heterostructures and reveal the epitaxial science governing their formation.

The local layer alignment in a wide range of trilayer graphene structures has been extracted by interferometric four-dimensional scanning transmission electron microscopy, uncovering the complex picture of lattice reconstruction in twisted trilayers.

Angle-resolved transport measurements on twisted trilayer graphene reveal evidence for a variety of correlated states with spontaneous symmetry breaking, and offer evidence of momentum polarization.

The direct and facile growth of WS₂ and WSe₂ nanotubes with controllable chirality is realized using catalytic chemical vapour deposition with Au nanoparticles.