Lifted graphene nanoribbons on gold: from smooth sliding to multiple stick-slip regimes

TL;DR

This study uses classical simulations to explore how graphene nanoribbons slide on gold surfaces, revealing the transition from smooth to stick-slip motion and the factors influencing frictional behavior.

Contribution

It provides a theoretical analysis of frictional regimes in GNRs on gold, highlighting the roles of edges, adhesion, lifting, and elasticity in stick-slip phenomena.

Findings

Stick-slip originates from 1D edges, not the bulk

Adhesion and lifting influence frictional behavior

Elasticity affects GNR sliding friction

Abstract

Graphene nanoribbons (GNRs) physisorbed on a Au(111) surface can be picked up, lifted at one end, and made slide by means of the tip of an atomic-force microscope. The dynamical transition from smooth sliding to multiple stick-slip regimes, the pushing/pulling force asymmetry, the presence of pinning, and its origin are real frictional processes in a nutshell, in need of a theoretical description. To this purpose, we conduct classical simulations of frictional manipulations for GNRs up to 30 nm in length, one end of which is pushed or pulled horizontally while held at different heights above the Au surface. These simulations allow us to clarify theoretically the emergence of stick-slip originating from the short 1D edges rather than the 2D "bulk", the role of adhesion, of lifting, and of graphene bending elasticity in determining the GNR sliding friction. The understanding obtained in this simple context is of additional value for more general cases.