Strong Interlayer Coupling in Twisted Transition Metal Dichalcogenide Moiré Superlattices

Abstract

Moiré superlattices in twisted van der Waals materials offer a powerful platform for exploring light–matter interactions. The periodic moiré potentials in moiré superlattices can induce strongly correlated quantum phenomena that depend on the moiré potential associated with interlayer coupling at the interface. However, moiré superlattices are primarily prepared by mechanical exfoliation and manual stacking, where the transfer methods easily cause interfacial contamination, and the preparation of high‐quality bilayer 2D materials with small twist angles by growth methods remains a significant challenge. In this work, WSe2/WSe2 homobilayers with different twist angles by chemical vapor deposition (CVD), using a heteroatom‐assisted growth technique, are synthesized. Using low‐frequency Raman scattering, the uniformity of the moiré superlattices is mapped to demonstrate the strong interfacial coupling of the CVD‐fabricated twist‐angle homobilayers. The moiré potential depths of the CVD‐grown and artificially stacked homostructures with twist angles of 1.5° are 115 and 45 meV (an increase of 155%), indicating that the depth of moiré potential can be modulated by the interfacial coupling. These results open a new avenue to study the modulation of moiré potential by strong interlayer coupling and provide a foundation for the development of twistronics.

Advance in twisted transition metal dichalcogenides: synthesis, characterization, and properties

“…In addition, t-MoS 2 with different twist angles also exhibits different shear and breathing mode characteristics. A similar phenomenon can be observed in other bilayer TMDCs materials [69,79,80], with shear mode and breathing mode having some angular dependence.…”

“…The OM images can be seen in figure 4(c). Zheng et al used a similar heteroatom-assisted growth strategy and gas disturbance strategy to successfully synthesize WSe 2 with twist angles of 1.5 • , 24 • , and 30 • etc [69]. In addition to the previously mentioned precursors, they also attempted to mix ammonium tungstate and KOH to prepare a tungsten source, and H 2 flow rate was adjusted to optimize the nucleation environment.…”

Twisted van der Waals Quantum Materials: Fundamentals, Tunability, and Applications

“…Many-Body Interactions. The moiréexcitons are produced from the periodic moirépotentials trapped interlayer excitons, 339,340 which inherit the spatially separated electrons and holes, exhibiting a permanent dipole moment, therefore providing an opportunity for studying many-body interactions and facilitating the strong correlation in the system. The dipole−dipole repulsive interactions among IXs have been widely reported in recent years, 31,341,342 which plays a crucial role in observing novel quantum phenomena such as superfluid, dipolar gases and dipolar crystals.…”

Moiré Synergy: An Emerging Playground by Coupled Moirés

“…Such moiré patterns in 2D heterostructures naturally form when two flakes of van der Waals (vdW) materials, including graphene and transition metal dichalcogenides (TMDCs), are stacked on top of each other with either a relative twist angle (for both homo- and heterobilayers) or a lattice mismatch (for heterobilayers). The prominent interlayer interactions , make the constituent atomic orbitals interfere constructively to manifest a superlattice of much larger wavelengths than the component lattice parameters, so that the energy band edges significantly flatten in the reciprocal space, nourishing a plethora of exotic quantum phenomena, such as superconductivity, correlated insulators, orbital magnetism, and unusual ferroelectricity . Notably, following the theoretic establishment of 2D ferroelectricity induced by interlayer translation, the experimental demonstrations of sliding ferroelectricity in various 2D stacks have boomed in the past few years. − …”