title: Critical length limiting superlow friction.
abstract: Since the demonstration of superlow friction (superlubricity) in graphite at nanoscale, one of the main challenges in the field of nano- and micromechanics was to scale this phenomenon up. A key question to be addressed is to what extent superlubricity could persist, and what mechanisms could lead to its failure. Here, using an edge-driven Frenkel-Kontorova model, we establish a connection between the critical length above which superlubricity disappears and both intrinsic material properties and experimental parameters. A striking boost in dissipated energy with chain length emerges abruptly due to a high-friction stick-slip mechanism caused by deformation of the slider leading to a local commensuration with the substrate lattice. We derived a parameter-free analytical model for the critical length that is in excellent agreement with our numerical simulations. Our results provide a new perspective on friction and nanomanipulation and can serve as a theoretical basis for designing nanodevices with superlow friction, such as carbon nanotubes.
authors.affiliation: School of Chemistry, Tel Aviv University, 69978 Tel Aviv, Israel.
authors.forename: Ming
authors.initials: M
authors.lastname: Ma
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Benassi
authors.affiliation: CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste, Italy and International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Vanossi
authors.affiliation: School of Chemistry, Tel Aviv University, 69978 Tel Aviv, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Urbakh