Frictional features in graphene nanoribbons deposited on gold

Guerra1,2, A. Benassi3,4, N. Manini5 and A. Vanossi1,2

1.International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy

2.CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste, Italy

3.Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, 01062 Dresden, Germany

4.Dresden Center for Computational Materials Science (DCCMS), TU Dresden, 01062 Dresden, Germany

5.Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy

We address the atomistic nature of the longitudinal static friction of graphene nanoribbons (GNRs) deposited on Au (111); the structural and mechanical properties of such graphitic nanostructures have been recently the subject of intense experimental investigation [1-4].

By means of numerical simulations and modeling we show that the bulk of the longitudinal friction originates at the front/tail edges of the ribbons which provide an extra graphene-gold interdigitation. By comparison with an open-boundary Frenkel-Kontorova model we explain the dependence of the total frictional force on the GNR length in terms of the increased compliance of the GNRs edges.

Supporting the experimental data, our model reveals a negligible frictional contribution of the internal “bulk” region of the ribbons. The edges dominate the total friction force which, as a result, does not grow with the GNR length, but rather oscillates around a fairly constant mean value in the 10 pN region, even at very large GNR length.

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