Shape-dependent friction scaling laws in twisted layered material interfaces

TL;DR

This paper investigates how the shape and orientation of layered material interfaces influence static friction and superlubricity, revealing shape-dependent scaling laws in twisted layered materials.

Contribution

It introduces shape-dependent friction scaling laws in twisted layered interfaces, highlighting the role of edge orientation and twist angle in superlubricity.

Findings

Friction scaling depends on shape and orientation.

Incomplete moiré tiles at edges influence static friction.

Shape tailoring can enable large-scale superlubricity.

Abstract

Static friction induced by moir\'e superstructure in twisted incommensurate finite layered material interfaces reveals unique double periodicity and lack of scaling with contact size. The underlying mechanism involves compensation of incomplete moir\'e tiles at the rim of rigid polygonal graphene flakes sliding atop fixed graphene or h-BN substrates. The scaling of friction (or lack thereof) with contact size is found to strongly depend on the shape of the slider and the relative orientation between its edges and the emerging superstructure, partially rationalizing scattered experimental data. With careful consideration of the flake edge orientation, twist angle, and sliding direction along the substrate, one should therefore be able to achieve large-scale superlubricity via shape tailoring.