Rotational Friction Correlated with Moiré Patterns in Strained Bilayer Graphene: Implications for Nanoscale Lubrication

Energy conservation of graphene nanodevices requires frictional dissipation management for their high surface area to volume rates, and rotational motion besides sliding scenarios appear frequently. Here, the rotational friction between graphene layers is investigated by molecular dynamics simulations with a validated graphene-spring model. It shows that the interlayer frictional torque drops an order of magnitude and approaches superlubricity with the emergence of Moiré patterns (MPs). Further analysis reveals that the incommensurate interface of MPs tunes the local energy, which cancels each other out with relative rotation, resulting in ultralow interlayer energy barriers. Accordingly, for bilayer systems with biaxially stretched substrates, a significant torque reduction can be achieved when the size of MPs matches that of the graphene flake. This study would provide new insight into the lubrication of rotatable nanomechanical systems.