Unveiling the moiré pattern evolution and superlubricity in twisted bilayer 2D phosphorene at atomistic scale

Abstract

Moiré patterns are commonly evidenced on two-dimensional (2D) van der Waals (vdW) bilayers stacked with rotational misalignment or slight lattice mismatch, which can dramatically influence the interface mechanical properties. Understanding the basic characteristics of moiré patterns are essential to tune the interfacial mechanical properties. Herein, molecular dynamics (MD) simulations are performed to capture the atomic evolution in the interface of the bilayer phosphorene during rotation and sliding. The hexagonal moiré patterns are observed in bilayer blue phosphorene, while the transition from quadrate to one dimensional stripe-like moiré pattern is evidenced in bilayer black phosphorene as the twist angle increases. However, the unique one-dimensional stripe-like moiré pattern always exists in black phosphorene/blue phosphorene heterogeneous interface during rotation. The reconstruction and deformation of Moiré pattern are determined by the competition between intralayer strain and interlayer coupling. The energy barrier for the rotation of heterogeneous bilayers is almost an order of magnitude smaller than that in homogeneous bilayers. As a result, the friction forces of heterogeneous bilayer during sliding can fall in the scope of superlubricity more possibly. However, the surface roughness, contact size and twist angle also alter the friction force. The results provide a comprehensive understanding on the Moiré superlattices.