The twisting dynamics of large lattice mismatch van der Waals heterostructures

TL;DR

This study investigates the twisting dynamics of MoS2/graphite heterostructures, revealing how structural potential energy changes influence rotational resistance, with implications for energy dissipation in 2D material interfaces.

Contribution

It provides the first detailed analysis of rotational motion mechanisms in vdW heterostructures, highlighting the role of structural potential energy and Moiré patterns in rotational resistance.

Findings

Rotational resistance depends strongly on twist angles.

Potential energy increases monotonically from 0 to 30 degrees.

Moiré superstructures control the energy landscape.

Abstract

Van der Waals (vdW) homo-/hetero-structures are ideal systems for studying interfacial tribological properties such as structural superlubricity. Previous studies concentrated on the mechanism of translational motion in vdW interfaces. However, detailed mechanisms and general properties of the rotational motion are barely explored. Here, we combine experiments and simulations to reveal the twisting dynamics of the MoS$_2$/graphite heterostructure. Unlike the translational friction falling into the superlubricity regime with no twist angle dependence, the dynamic rotational resistances highly depend on twist angles. Our results show that the periodic rotational resistance force originates from structural potential energy changes during the twisting. The structural potential energy of MoS$_2$/graphite heterostructure increases monotonically from0 to 30 degrees twist angles, and the estimated relative energy barrier is (1.43 +/- 0.36) x 10 J/m. The formation of Moir\'e superstructures in the graphene layer is the key to controlling the structural potential energy of the MoS$_2$/graphene heterostructure. Our results suggest that in twisting 2D heterostructures, even if the interface sliding friction is negligible, the evolving potential energy change results in a non-vanishing rotational resistance force. The structural change of the heterostructure can be an additional pathway for energy dissipation in the rotational motion, further enhancing the rotational friction force.