(Invited) Controlling the Layer Stacking and Twisting of 2D Quantum Materials

Abstract

Rationally and precisely controlling the structures of two-dimensional (2D) layered materials allows us to tune the electronic structures and quantum states of matter, discover new physical properties, thus enable new applications. For example, tuning the twist angles between 2D materials results in the formation of moiré patterns and the manipulation of electronic states, which have led to novel quantum phenomena, including unconventional superconductivity, moiré excitons, and tunable Mott insulators. We have shown how the phase, layer stacking and thus physical properties of 2D MX2 materials can be influenced by screw dislocations. Moreover, we achieved systematic interlayer twisting of MX2 spiral layers grown via by screw dislocations due to mismatched geometry between Euclidean crystal lattices and non-Euclidean (curved) surfaces (Science 2020, 370, 442). We experimentally demonstrated the growth of twisted spirals of WS2 and WSe2 draped over nanoparticles near their centers and microscopic structural analysis confirmed the moiré superlattices between the atomic layers. Tuning the stacking and twisting of 2D materials opens up new dimensions of 2D quantum materials (Acc. Mater. Res. 2022, 3, 369) for the study of moiré excitons, nonlinear optical properties, chiral optoelectronics, valleytronics and twistronics.