Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 69: Nanostructures at surfaces: 1D and 2D structures and networks II

O 69.1: Vortrag

Mittwoch, 14. März 2018, 15:00–15:15, MA 141

Graphene nanoribbons on gold: superlubricity and edge effects — •Lorenzo Gigli — SISSA (International School of Advanced Studies), Via Bonomea 265, Trieste (TS), Italy

Via numerical simulations, we investigate the static structural features and the frictional response of n = 7 armchair graphene nanoribbons (GNRs) of different lengths deposited on a gold Au(111) substrate, a tribological interface subject of recent, intense experimental studies. The C-Au lattice mismatch and the GNR-substrate relative orientation dictate the periodicity of the interface Moire' pattern for the relaxed GNR configurations. By adiabatically increasing an uniform external force directed along the longitudinal GNR axis, the molecular-dynamics approach shows a static frictional response which does not grow with the GNR length, thus supporting the experimental data of a superlubric behavior with negligible frictional contribution of the internal bulk region of the ribbon. The peculiar oscillatory trend of the static friction versus length, around a fairly constant mean value (tens of pN), correlates with the characteristic modulation of the observed Moire' pattern (2D Materials 4, 045003, 2017).

Mimicking the experimental framework by Kawai et al. (Science 351, 957, 2016), we also present results of the dynamical response of deposited GNRs, lifted at one end and pulled laterally by a spring moving at constant velocity. Competition between peeling and sliding mechanisms, stick-slip and smooth dynamics are discussed in terms of the edge-lifting height and the effective GNR elasticity.